Development cooperation has created a range of instruments to support private companies wishing to invest in partner countries whilst also pursuing development goals. These instruments are primarily expected to mobilise the additional funding needed to finance the Sustainable Development Goals (SDGs). But as to how far private sector engagement is achieving this and other objectives, until now the only research has taken the form of evaluations and academic studies on individual projects and instruments. In the evaluation synthesis by DEval (Habbel et al., 2021) the available evidence on private sector engagement is analysed systematically for the first time. This policy brief summarises the most important findings and recommendations from the evaluation synthesis by DEval.