Behavioural activation is effective for depression, but its effectiveness in treating adults with depression when delivered by lay workers remains unclear.

To examine the effectiveness of behavioural activation delivered by lay workers, compared with any control group, in reducing depressive symptoms in adults.

This systematic review searched six databases from inception to January 2025, for randomised controlled trials (RCTs) comparing behavioural activation and any control conditions for individuals with depression when delivered by lay workers. Additional searches were conducted in the international trial registries and reference lists (PROSPERO registration CRD42024625620). Risk of bias was assessed using the Cochrane Collaboration’s Risk-of-Bias 2 tool. Random effects meta-analysis was conducted using the Metafor package in R.

Of 9614 initial studies, six RCTs met the inclusion criteria and were included. A total of 1118 participants in the intervention groups and 1596 in the control groups. The findings demonstrated a small but statistically significant effect in reducing depressive symptoms in favour of the intervention group (standardised mean difference: −0.28, 95% CI −0.46 to −0.09; p = 0.0029). However, the risk of bias was high across all studies, with substantial heterogeneity (I2 = 76%).

Evidence from this review and meta-analysis suggests that behavioural activation, when delivered by trained lay workers, may offer an effective approach for reducing depressive symptoms in adults, particularly in settings with limited access to specialist mental healthcare professionals. However, high risk of bias and heterogeneity of the included studies means that these findings should be interpreted with caution.