How to Write a Case Study for a Service Business (With Examples)

For service businesses such as agencies, consultancies, accountants and contractors, a case study is often the most persuasive piece of marketing they own. Prospects cannot try a service before buying, so they look for evidence that you have done similar work well. This guide focuses on writing practical case studies for service firms, including short formats that take an hour to produce. For the in-depth B2B process, including customer interviews, see our guide to B2B case study writing.

Three Formats Worth Having

A Simple Story Structure

1. The client and the situation: who they are and what was happening.
2. The challenge: what they needed and why it was difficult.
3. What we did: your approach, decisions and the work delivered.
4. The result: what changed for the client.
5. In their words: a short quote.

Example: A Micro Case Study

Regional dental group, website rebuild. Eight clinics, eight outdated websites and no online booking. We built one site with clinic pages and integrated booking. In the first three months, online bookings rose from zero to about a quarter of new appointments, and front-desk calls fell. "Our receptionists finally have time for patients in the room." Practice manager.

The details here are illustrative. In a real case study, every figure must be accurate and approved by the client.

Writing Results When Numbers Are Limited

Not every project produces neat metrics. Describe concrete changes instead: a process that now takes one meeting instead of three, a launch delivered before a key event, a compliance audit passed, a team that no longer needs outside help for a task. Qualitative results stated specifically are still persuasive. Avoid inventing or estimating numbers the client has not confirmed.

Laying Out a Case Study Page

• A headline stating the result.
• A summary box with client, sector, services and key outcomes.
• Short sections following the story structure.
• Images of the work where relevant: screenshots, photos, before-and-after.
• A quote, visually highlighted.
• A call to action to discuss a similar project.

Getting Permission

Ask clients early, ideally when the project goes well, and explain where the case study will appear. Offer them review of the final text. If they prefer anonymity, describe them by sector and size, and still focus on specific work and outcomes.

Example: A Standard Case Study Outline

Headline: How a family law firm doubled consultation bookings with a clearer website. Summary box: client, sector, services provided, key outcome. The situation: a respected firm whose website described services in legal terms that clients did not understand. The challenge: enquiries came mainly by phone, and many were from people the firm could not help. What we did: interviewed recent clients, rewrote service pages in plain language, added a simple enquiry form that asked the right questions. The result: more relevant enquiries and fewer unsuitable calls, with figures confirmed by the client. Quote: a partner on what changed for the team. This outline can be written in an afternoon once the facts are gathered.

Collecting Material as You Go

The easiest case studies are the ones planned from the start of a project. Record baseline figures before work begins, keep notes on key decisions, save before-and-after images, and ask the client for a quick reflection at the end. Building this into your project process means you always have material ready when a strong case study opportunity arises.

Mistakes to Avoid

• Focusing on your process rather than the client's outcome.
• Vague results such as "improved performance".
• Jargon the prospect does not understand.
• No quote from the client.
• Publishing without the client's approval.