The Modern Slavery Act 2015 requires large firms doing business in the UK to disclose their efforts to prevent modern slavery within their global supply chains. This paper considers the extent to which companies have complied with the Act and provides an insight into engagement with its underlying objectives. This is achieved through a content analysis of the modern slavery statements published by 934 companies in 2016. As the largest systematic review of UK modern slavery reporting, this paper has international implications due to the globalized nature of modern slavery and the sizeable international shareholder base in large UK companies.