What Does a Principal Engineer Do?
Module 3 of 4 Intermediate 25 min

One Title, Three Flavours — The Types of Principal Engineers

Prerequisites: How Engineers Level Up — The Career Ladder and Its History, Two Paths Forward — How Tech Companies Let Great Engineers Stay Engineers

What You'll Learn

  • How the seniority spectrum above Senior Engineer works — from Staff Engineer all the way to Fellow — and what distinguishes each level.
  • Why a Principal Engineer is different from a Staff Engineer, in plain language you can repeat at the dinner table.
  • The three archetypes of Principal Engineers — Architect, Solver, and Generalizer — and why all three matter to a company.
  • Why most real Principal Engineers blend more than one archetype, and why that is a feature, not a flaw.

Why This Matters

You have probably noticed that job titles in tech are everywhere — and mostly opaque. "Senior Engineer," "Staff Engineer," "Principal Engineer," "Distinguished Engineer": without a map, these titles blur together into one long word soup. But the distinctions are real and meaningful, and understanding them will help you make sense of how large technical organizations actually function.

More specifically, even within the title "Principal Engineer," there is genuine variety. Two people can both be Principal Engineers at the same company, both at the same salary band, and spend their weeks doing almost completely different things. One might be the person everyone calls at 2 a.m. when the payment system goes down. Another might spend most of their time writing documents that no single team requested but that every team ends up following. Understanding these patterns helps you see the role more clearly — and helps Sarah explain her own job in a way that actually lands.

Core Concept

The Seniority Spectrum Above Senior Engineer

You met these levels briefly in Module 01 — here we look at them again with attention to how they differ in practice.

In an earlier module, you learned how the career ladder works: engineers move through levels as their scope and responsibility grow. Once an engineer reaches the top of the early rungs, the ladder continues with four more levels, each representing a broader organizational reach — how many teams, products, or people are affected by an engineer's decisions.

Here is the full sequence above Senior Engineer:

Staff Engineer → Principal Engineer → Distinguished Engineer → Fellow

Think of these four levels as expanding rings of impact.

A Staff Engineer is a domain expert whose organizational reach spans multiple teams within one area. They might own the technical direction for a company's payments infrastructure, or for its mobile app platform. They are the go-to expert for a defined zone of the company. Their decisions affect ten or twenty teams — the ones working in their area.

A Principal Engineer is a senior individual contributor whose organizational reach spans the whole company; they shape technical strategy, mentor others, and make architectural decisions that affect dozens of teams, without managing anyone directly. Where a Staff Engineer is the expert of their neighborhood, a Principal Engineer is thinking about the whole city.

A Distinguished Engineer is a Principal-level-or-above individual contributor whose technical decisions carry company-defining weight; typically there are only a small number per company. A Distinguished Engineer might be the person who defined how the company's core technology works — not just which tools to use, but the foundational approaches that everything else is built on.

A Fellow is the highest individual contributor title; extraordinarily rare — a handful per company. A Fellow's work is treated as foundational to the company's technical identity. You might recognize some of them by name if you have followed the history of the internet: the people who invented the protocols and programming languages we all use today often held Fellow-equivalent titles.

The Critical Staff vs. Principal Distinction

The boundary between Staff Engineer and Principal Engineer is the one most worth understanding clearly, because it is the most commonly blurred.

The cleanest way to state it: A Staff Engineer is a domain expert whose reach spans multiple teams within one area; a Principal Engineer is an organizational strategist whose reach spans the whole company.

Here is a concrete test. Imagine Sarah's company is deciding whether to move from one database system (the software that stores all the company's records) to a newer one. Who gets asked?

A Staff Engineer who specializes in databases will almost certainly be asked — they know that technology deeply. But they will be giving advice specifically about the database: can the new system handle the company's workload? How risky is the migration?

A Principal Engineer will be asked a different set of questions: Should the company make this move at all, given its five-year product strategy? Which other teams will be disrupted, and is now the right time? What does this decision lock the company into for the next decade?

The Staff Engineer brings depth. The Principal Engineer brings breadth and time-horizon. Neither is more valuable — both are essential — but they are genuinely different roles.

The Three Archetypes

Even within the Principal Engineer level, different people work in recognizably different ways. The engineering community has settled on three broad patterns — called archetypes — to describe these variations.

Archetype 1: The Architect

The Architect sets technical standards, reviews major system designs, and defines the rules that everyone else must follow. They are less likely to be the ones writing new code from scratch, and more likely to be the ones whose approval is required before a major piece of code gets built. Their output is often documentation: standards documents, design review frameworks, architectural principles.

Think of a city's chief building inspector: they don't build every house, but they approve every blueprint, and they set the codes that determine what structures are even allowed.

Archetype 2: The Solver

The Solver is called in when a critical problem has stumped everyone else. They have deep expertise — often in one technical area — and are the person organizational leadership turns to when something is broken in a way nobody can explain, or when a project is in serious trouble and needs a clear path forward.

The Solver's value is partly technical and partly diagnostic: they can figure out what is actually wrong, not just apply a standard fix. Their work tends to be episodic — they parachute into a crisis, resolve it, and move on to the next one.

Archetype 3: The Generalizer

The Generalizer connects the dots across the whole organization. They know enough about every area to spot when two teams are about to make incompatible decisions, or when a solution developed in one part of the company could solve a problem that another team has been struggling with for months.

The Generalizer is rarely the deepest expert in any one area — but they are often the only person who can see how all the areas relate to each other. In a company of five hundred engineers working on dozens of different systems, that bird's-eye view is irreplaceable.

Archetypes Are a Mental Map, Not a Job Description

It is important to say clearly: most real Principal Engineers blend two of these archetypes, and many shift between them over their career. The taxonomy is a mental map to help you see the different kinds of work the title covers — not a rigid classification that anyone is locked into. At any given company, the distribution will depend on what that company most needs.

The broader industry uses slightly different labels in some contexts. Will Larson's influential book on the topic (staffeng.com) describes four archetypes at the Staff and Principal levels: Tech Lead, Architect, Solver, and Right Hand. The "Generalizer" in this module maps roughly to the "Tech Lead" pattern in that framework. Same essential ideas, different vocabulary — which is itself a good reminder that none of these taxonomies are official standards.

Concrete Example

Sarah's sibling has been listening carefully, and now asks: "But are all Principal Engineers the same? Like, do they all do the same job?"

Sarah shakes her head. "Not at all. Let me tell you about three colleagues of mine."

Priya is also a Principal Engineer at Sarah's company. Priya's work is mostly invisible day-to-day, but her fingerprints are everywhere. She spent the past year writing the company's API design standards — a document that specifies exactly how all the company's software systems should talk to each other. Every team followed it when they built new features this quarter. Priya never wrote a single line of those features. But because her standards were clear, all those features work together seamlessly. Priya is the Architect.

Marcus is the person you hope you never need — because if you need Marcus, something has gone seriously wrong. Last spring, the company's order processing system (the software that handles every customer purchase) started failing in a way nobody could explain. The engineering team spent three days on it. Then Marcus came in. Within two days, he had traced the problem to an interaction between three different systems that no one had thought to look at together. He fixed it, wrote up what he found, and moved on to the next crisis at another company division. Marcus is the Solver.

Sarah is herself the third type. She does not specialize in one technology, and she is not the company's greatest expert in any single area. What she does is notice things. She was in a meeting last month where the mobile team described a problem they had been stuck on for weeks — and immediately realized that the data team had solved an almost identical problem six months ago and never documented it. She connected them. The mobile team had their answer in a week. Sarah is the Generalizer.

"So Priya sets the rules," her sibling says. "Marcus puts out fires. And you're the one who makes sure the left hand knows what the right hand is doing."

Sarah smiles. "That's exactly it."

Analogy

Think of a symphony orchestra.

The orchestra has section leaders — the first-chair violin, the principal oboist, the lead cellist. Each of those section leaders is the best player in their section, and they set the standard for how that section performs. They are the Staff Engineers of the orchestra: deep experts in their domain, responsible for a defined group.

But the Principal Engineer equivalent is the conductor. The conductor does not play any instrument. Their job is to hear how all the sections sound together, to make adjustments that no single section leader can make, and to hold the overall interpretation of the music in their head. When the brass section overpowers the strings, the conductor notices. When the tempo needs to shift to let a soloist breathe, the conductor signals it.

Within conductors, you even see the same archetypes. Some conductors are famous for their strict adherence to the score — setting standards and insisting on precision (Architect). Some are brought in specifically to rescue a struggling production (Solver). Some are celebrated for their ability to blend styles and bring out the best in every instrument across the full orchestra (Generalizer).

The music only works because all three types of leadership are present.

Going Deeper

The archetype framework described here — Architect, Solver, Generalizer — is a simplified version of a richer taxonomy that has developed in the industry over the past two decades.

Will Larson's book Staff Engineer: Leadership beyond the management track (2021) is the most widely cited framework. He describes four archetypes: Tech Lead, Architect, Solver, and Right Hand. The Right Hand is the rarest — it appears only at very large companies (typically a thousand or more engineers) and involves working almost like an extension of a senior executive, taking on organizational problems that are too complex and too high-stakes for anyone else to handle.

Different companies have developed their own versions of this taxonomy internally. Dropbox, for instance, publishes its career framework publicly and defines distinct archetypes and behaviors for engineers at the Principal level. These internal frameworks tend to be more specific and more tied to the company's own systems and culture.

The meta-lesson is worth holding onto: the engineering community has found it genuinely useful to recognize that there is more than one way to be a great senior individual contributor. Rather than forcing all Principal Engineers into a single mold, good organizations learn to identify which archetype a person naturally gravitates toward — and then create conditions for that person to thrive in that pattern.

That said, some researchers and practitioners have pushed back on the archetype framework, arguing that it can become a constraint: if someone is labeled an "Architect," they may not be given the chance to develop their problem-solving skills. The best companies treat archetypes as a descriptive tool, not a prescriptive box.

Common Misconceptions

Misconception 1: "A Principal Engineer is just a Staff Engineer with more experience."

This is understandable — they are adjacent levels on the same ladder — but it misses the qualitative shift in scope. A Staff Engineer is optimizing within a domain; a Principal Engineer is making decisions that determine which domains the company should invest in at all. The difference is not more of the same work; it is a different kind of work. More experience is part of what gets you there, but it is not what defines the role.

Misconception 2: "The archetypes are official job descriptions that companies use."

They are not. The Architect/Solver/Generalizer framework (and Will Larson's four-archetype model) are frameworks that practitioners and writers developed to describe patterns they observed. Most companies do not use these words in their job postings or their internal career frameworks. They are useful lenses for understanding the variety within the title — not official categories you will find on an org chart.

Misconception 3: "A Principal Engineer who isn't writing code isn't doing their job."

At earlier levels in the career ladder, the majority of an engineer's contribution comes from writing code. At the Principal level, that ratio shifts significantly. A Principal Engineer might spend most of a week in meetings, reviewing documents, writing strategy papers, or mentoring — and that is the correct use of their time. Their organizational reach is the measure of their contribution, not their lines of code. Holding a "is this person coding enough?" standard to a Principal Engineer misunderstands what the role is for.

Check Your Understanding

  1. In your own words, what is the key difference between a Staff Engineer and a Principal Engineer? Try to explain it without using the words "more" or "better."

    Reveal answer A Staff Engineer is a domain expert whose organizational reach spans multiple teams within one area. A Principal Engineer is an organizational strategist whose organizational reach spans the whole company. The distinction is not seniority alone — it is the scope of what they are responsible for thinking about. A Staff Engineer owns a domain; a Principal Engineer thinks about how all the domains fit together.

  2. Sarah's colleague Priya spent a year writing a standards document that every team now follows. Which archetype does Priya fit, and why? What would it look like if Priya were a Solver instead?

    Reveal answer Priya is an Architect — she defines the rules and standards that shape how other engineers work, without building the features herself. If Priya were a Solver, her work would look different: she would be brought in to specific crises or deeply knotty technical problems, apply her expertise to resolve them, and then move on. She would be less focused on setting enduring standards and more focused on resolving immediate, high-stakes situations.

  3. Sarah's sibling summarizes the three archetypes as: "Priya sets the rules. Marcus puts out fires. Sarah makes sure the left hand knows what the right hand is doing." Is this a fair summary? What does it leave out?

    Reveal answer It is a fair and vivid summary. What it leaves out is the organizational reach dimension — all three are affecting hundreds of engineers across the whole company, not just their immediate teams. It also leaves out the blending aspect: Sarah might take on an Architect role occasionally when she spots a gap in the company's standards, and Marcus might share his hard-won knowledge in a way that sets standards for how future crises are handled. The summary captures the flavor of each archetype well, but real engineers are not quite as neatly separated.

  4. The module notes that the staffeng.com framework uses four archetypes (Tech Lead, Architect, Solver, Right Hand) while this module uses three (Architect, Solver, Generalizer). Why might two frameworks for the same idea use different categories? Does this mean one of them is wrong?

    Reveal answer Neither is wrong — they are both useful descriptions of real patterns, developed from observing real engineers. Different frameworks emphasize different things. Larson's "Right Hand" archetype applies mainly at very large companies and is absent from smaller ones. The "Generalizer" label emphasizes the cross-domain connective role more explicitly than "Tech Lead" does. The existence of multiple frameworks is itself informative: it tells you that these are observed patterns, not official job descriptions, and that the patterns look slightly different depending on company size and context.

  5. Why does the module describe the archetypes as "a mental map, not a rigid job description"? What could go wrong if a company treated them as rigid categories?

    Reveal answer If archetypes become rigid boxes, they can limit people. An engineer labeled an "Architect" might not be given problems that would develop their Solver skills. An engineer who is primarily a Solver might not be given the space to develop enduring standards — even when that is what the company needs most from them. The archetype framework is meant to help companies understand the variety within the Principal Engineer level and deploy people well, not to lock anyone into a single pattern permanently.

Key Takeaways

  • The seniority spectrum above Senior Engineer follows this sequence: Staff Engineer → Principal Engineer → Distinguished Engineer → Fellow — each level representing broader organizational reach and higher-stakes decisions.
  • The canonical distinction: a Staff Engineer is a domain expert whose organizational reach spans multiple teams within one area; a Principal Engineer is an organizational strategist whose organizational reach spans the whole company.
  • There are three archetypes of Principal Engineers — the Architect (sets standards and rules), the Solver (resolves the hardest problems), and the Generalizer (connects knowledge and people across the whole organization) — and most real Principal Engineers blend two of them.
  • These archetypes are a descriptive mental map, not official job titles; the broader industry uses slightly different labels (including Tech Lead and Right Hand), and no single taxonomy is universal.
  • The measure of a Principal Engineer's contribution is their organizational reach — how many teams and decisions their work shapes — not how many lines of code they write.

References

In the next module, we follow Sarah through a real week — Monday through Friday — to see what these archetypes look like in practice, hour by hour. We know the types; now let's see the work.