Purpose: Participatory extension programmes are widely used to promote change in the agricultural sector, and an important question is how best to measure the effectiveness of such programmes after implementation. This study seeks to understand the current state of practice through a review of ex post evaluations of participatory extension programmes. Design/methodology/approach: A systematic literature review of the peer-reviewed literature was undertaken to analyse the evaluations based on: (i) year of publication; (ii) location of the study; (iii) programme delivery; (iv) evaluation methods; (v) outcome variables; and (vi) inclusion of evaluation in initial programme design. Findings: The review finds that almost all studies use an experimental or quasi-experimental research design (i.e. using a control group or counterfactual), but some studies do not account for endogeneity or selection bias. Furthermore, only a small number of the evaluations were planned as part of the original programme design, which causes difficulties in obtaining robust counterfactuals. The review also finds that relatively few evaluations, approximately 20%, measure the programme impact on environmental outcomes and only 15% of the evaluations have been undertaken for programmes in developed countries. Practical implication: Limitations with current evaluation practice are identified, and recommendations are provided for improving practice, including better treatment of endogeneity, and the complementary use of qualitative data. Theoretical implication: The review provides a contribution to the debate about the use of quantitative versus qualitative evaluation methods, by addressing the use of both quantitative and qualitative evaluation methods in a complementary way. Originality/value: Despite their widespread implementation, this is the first systematic literature review for published evaluations of participatory extension programmes in the agricultural sector.