Existing tools for evaluating psychosocial interventions (un-validated self-reporting questionnaires) are not ideal for use in non-Western conflict settings. We implement a generic method of treatment evaluation, using client and counsellor feedback, in 18 projects in non-Western humanitarian settings. We discuss our findings from the perspective of validity and suggestions for future research. A retrospective analysis is executed using data gathered from psychosocial projects. Clients (n = 7,058) complete two (complaints and functioning) rating scales each session and counsellors rate the client's status at exit. The client-completed pre- and post-intervention rating scales show substantial changes. Counsellor evaluation of the clients' status shows a similar trend in improvement. All three multivariable models for each separate scale have similar associations between the scales and the investigated variables despite different cultural settings. The validity is good. Limitations are: ratings give only a general impression and clinical risk factors are not measured. Potential ceiling effects may influence change of scales. The intra and inter-rater reliability of the counsellors' rating is not assessed. The focus on client and counsellor perspectives to evaluate treatment outcome seems a strong alternative for evaluation instruments frequently used in psychosocial programming. The session client rated scales helps client and counsellor to set mutual treatment objectives and reduce drop-out risk. Further research should test the scales against a cross-cultural valid gold standard to obtain insight into their clinical relevance.