This review summarises existing studies evaluating the impact of apprenticeships on individuals and firms and provides a brief overview of relevant evaluations in three related policy areas: education; active labour market programmes; and private on-the-job training. Based on the reviewed literature, it draws a number of lessons that are relevant for evaluating apprenticeship programmes in OECD member countries, such as the Modern Apprenticeships in Scotland. First, rigorous evaluation depends on the existence of suitable, high-quality data. Second, the measured effects of apprenticeships depend on the time elapsed since the end of the training period. Third, the outcomes most commonly examined in the existing literature are wages and the probability of employment. Fourth, it is important to employ methods that take into account not only observed but also unobserved individual characteristics. Finally, comparing apprentices to different "control groups" might provide different and complementary evidence on the impact of apprenticeships.