This document summarizes a study on the use of social media in recruitment conducted by the Institute for Employment Studies (IES) for the UK's Advisory, Conciliation and Arbitration Service (Acas). The study aimed to understand how and why employers use social media tools for recruitment, the perceived costs and benefits, and the legal and reputational risks. It involved a literature review and case studies with Pets at Home, G4S, and Monmouthshire County Council. The study found that employers use social media mainly for candidate screening and marketing, though there are risks around privacy, discrimination, and bias. Employers must develop policies around social media use in recruitment to manage these risks.