Two observations on how SRE teams are composed. **Diversity makes better teams.** SRE spans systems engineering, software engineering, and organization/management skills, and there's substantial evidence that **diverse teams are simply better** — which improves the odds of successful collaboration. Running a diverse team demands particular attention to communication and cognitive biases. **Three formal roles**, on a fluidity spectrum: - **Tech Lead (TL)** — responsible for technical direction; leads via code comments, quarterly direction talks, or consensus-building. At Google, TLs can do almost all of a manager's job because managers are highly technical. - **Manager (SRM)** — adds two things a TL doesn't have: the **performance-management function**, and being the **catchall** for anything no one else handles. - **Project/Program Manager (TPM/PgM).** The fluidity tradeoff: **well-defined responsibilities** let people make in-scope decisions quickly and safely; **fluid, dynamically-negotiated** responsibilities make a team more adaptable — but at the cost of **more frequent communication**, because less background can be assumed. The more capable the individuals, the more a team can afford to run fluid. Great TLs/SRMs/TPMs have the full skill set and switch freely between organizing, design review, and writing code.