Preface
We’re writing this in the middle of 2026, and some of what follows will be out of date by the time you read it. That’s the nature of the moment — AI is developing faster than books can be printed. Our own thinking changed while we wrote this edition, and it’ll keep changing after.
The mechanics of building software are in motion: how teams are shaped, and how much coordination it takes now that an engineer can produce in a day what used to take a week. As more organizations rebuild themselves around agents, those mechanics keep shifting — and the faster they do, the more it costs to get the fundamentals wrong.
It’s tempting to read all that speed as progress. But while AI does make individual engineers faster at producing code, it does not, on its own, make an organization faster at delivering software.
How quickly value reaches a customer depends on the system around the code: how work gets prioritized, how teams coordinate, how changes get reviewed and shipped, how quality holds up, and how the organization learns from what it builds. That’s the work that turns code into something people actually use, and it’s where the potential lies. Speed up one step inside that system and you’ve changed very little. Improve the system, and everything gets better.
Effective engineering organizations have always rested on the same foundations: building around outcomes and customer value, keeping quality high, continuously improving how they work — and knowing none of it holds together without taking care of the people doing the work.
That’s why this book is about how to reason about engineering effectiveness. When everything around you is in flux, knowing why something works is what allows you to adapt it to your own situation rather than importing a solution built for someone else.
So this book won’t give you a one-size-fits-all playbook — those don’t work, and the people selling them know it. Instead, it offers a way to honestly assess where you are, find your highest-leverage opportunities, and build an approach to effectiveness that fits your organization.
If this matters to you as much as it does to us, this book is for you.