We explore how four evidence-producing organisations in the US go ahead when they rate the evidence base for psychosocial interventions, using the Incredible Years programme as our case study. The findings demonstrate variation in the procedures and resulting evidence claims across the organisations, with some organisations being strict and some being permissive. The presence of such conflicting practices highlights central challenges for the evidence-based practice framework and its ambition of obtaining uniform evidence statements. We conclude that practitioners and policy makers should be aware of such variation in order to be able to make informed decisions regarding which programmes to use.