This article is the result of a review of the impact and effectiveness of Transparency and Accountability Initiatives (TAIs). These TAIs have taken democratisation, governance, aid and development circles by storm since the turn of the century – and many people are keen to better understand what they are achieving. The review was based on the extensive gathering and analysis of both literature and documentation, and provided conclusions and recommendations for improvements. This article, as well as giving a background to social accountability and TAIs, summarises both what, and how methodologically, we know about their effectiveness and impact. It also pinpoints the factors that determine impact and concludes with a look at gaps in current knowledge and practice and recommendations for addressing these.