Note: If you’ll forgive the shameless self-promotion, applications for my MATS stream are open until Sept 12. I help people write a mech interp paper, often accept promising people new to mech interp, and alumni often have careers as mech interp researchers. If you’re interested in this post I recommend applying! The application should be educational whatever happens: you spend a weekend doing a small mech interp research project, and show me what you learned.

Last updated Sept 2 2025

TL;DR

This post is about the mindset and process I recommend if you want to do mechanistic interpretability research. I aim to give a clear sense of direction, so give opinionated advice and concrete recommendations.
- Mech interp is high-leverage, impactful, and learnable on your own with short feedback loops and modest compute.
- Learn the minimum viable basics, then do research. Mech interp is an empirical science
Three stages:
- [...]

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Outline:

(00:45) TL;DR

(06:26) Introduction

(07:42) High-Level Framing

(09:36) Stage 1: Learning the Ropes

(10:41) Machine Learning & Transformer Basics

(13:22) Mechanistic Interpretability Techniques

(15:57) Mechanistic Interpretability Coding & Tooling

(19:40) Understanding the literature

(22:45) Using LLMs for Learning

(27:38) Interlude: What is mech interp?

(31:27) The Big Picture: Learning the Craft of Research

(33:24) Unpacking the Research Process

(37:04) What is research taste?

(38:28) Stage 2: Practicing Research with Mini-Projects

(39:28) Choose A Project

(43:04) Practicing Exploration

(45:51) Practicing Understanding

(48:09) Using LLMs for Research Code

(49:33) Interlude: What's New In Mechanistic Interpretability?

(49:56) Avoiding Fads

(53:58) What's New In Mech Interp?

(01:00:10) A Pragmatic Vision for Mech Interp

(01:01:42) Stage 3: Working Up To Full Research Projects

(01:03:12) Key Research Mindsets

(01:09:22) Deepening Your Skills

(01:16:59) Practicing Ideation

(01:21:19) Write up your work!

(01:27:33) Mentorship, Collaboration and Sharing Your Work

(01:28:02) So what does a research mentor actually do?

(01:30:23) Advice on finding a mentor

(01:35:53) Community & collaborators

(01:37:54) Careers

(01:37:57) Where to apply

(01:39:30) What do hiring managers look for

(01:42:44) Should you do a PhD?

The original text contained 36 footnotes which were omitted from this narration.

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First published:
September 2nd, 2025

Source:
https://www.lesswrong.com/posts/jP9KDyMkchuv6tHwm/how-to-become-a-mechanistic-interpretability-researcher

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Narrated by TYPE III AUDIO.

“How To Become A Mechanistic Interpretability Researcher” by Neel Nanda

LessWrong (30+ Karma)