Complete Guide

How to Write a CLAUDE.md File

Claude treats you like a stranger at the start of every conversation. A CLAUDE.md fixes that permanently — here's exactly how to write one that works.

What is a CLAUDE.md file?

A CLAUDE.md is a plain-text file that sits at the top of your Claude project. Claude reads it before every single conversation — before you type a word. It's a permanent briefing: who you are, how you work, what you need, and what you don't.

Without one, Claude starts every chat as if it's meeting you for the first time. You re-explain your job. You re-specify your tone. You re-describe your audience. Then you do it again tomorrow. A good CLAUDE.md ends that loop.

Think of it as a standing instruction document — the kind you'd give a new team member on day one. "Here's what we do, here's how we write, here's what a finished deliverable looks like." A CLAUDE.md gives Claude that brief once, and it holds for every conversation in the project.

What a CLAUDE.md actually changes

The difference isn't subtle. These are real prompts — same task, same Claude, with and without a CLAUDE.md.

Freelance Writer

Without a CLAUDE.md, Claude writes to a generic audience in a generic voice. With one, it knows your byline, your clients, and your house style.

Before — no CLAUDE.md
After — with CLAUDE.md
Prompt: "Write a lede for my article on remote work burnout."
Remote work has transformed how we work, but it has also brought new challenges. Many employees are experiencing burnout as the lines between work and personal life blur...
Same prompt — Claude knows your voice and Fast Company audience:
The commute is gone. The 9-to-5 never left. For a growing number of remote workers, the problem isn't that they brought the office home — it's that the office never leaves.

Startup Founder

Without context, Claude gives you the MBA playbook. With a CLAUDE.md, it gives you advice calibrated to your actual stage, market, and constraints.

Before — no CLAUDE.md
After — with CLAUDE.md
Prompt: "How should I approach enterprise sales?"
Enterprise sales typically involves identifying key decision-makers, building relationships across the organization, and demonstrating ROI through a structured pilot process...
Same prompt — Claude knows you're pre-Series A, selling to healthcare ops teams:
Healthcare ops teams make you earn every inch. Skip the ROI deck for now — they won't believe it without a pilot. Get to the director of operations, not IT. Lead with time savings on scheduling, not cost.

Marketing Consultant

Without context, Claude produces generic strategy docs that look like a blog post. With one, it applies your frameworks and formats deliverables the way your clients expect.

Before — no CLAUDE.md
After — with CLAUDE.md
Prompt: "Draft a positioning statement for my client, a B2B SaaS company."
For [target customer] who [need or opportunity], [product name] is a [product category] that [key benefit]. Unlike [competitive alternative], our product [primary differentiation].
Same prompt — Claude knows your April Dunford framework and client voice:
Target: RevOps leads at 50-200 person B2B SaaS companies. Alternative: spreadsheets and Salesforce reports. Unique attribute: closes the loop between pipeline data and next action. Value: reps stop missing follow-ups; managers stop chasing updates.

5 tips for a great CLAUDE.md

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