Background: Cognitive representations of challenging behaviour among staff may influence therapeutic outcomes. This study looked at how cognitive dimensions of Identity, Cause, Consequences, Emotional Reaction and Treatment/Control are affected by training. Materials and Methods: A theoretically derived questionnaire was used to measure the impact of an accredited training course. There were two experimental designs: a longitudinal design using participants as their own controls for repeated measures, and a comparative subjects design. All participants were staff working in statutory and voluntary care services. Results: The experimental group outperformed the two control groups by more than would be expected, on the basis of pre-testing, on two of the five dimension measures, Cause and Treatment/Control. Conclusions: It is important to evaluate outcomes of staff training that seeks to improve staff interactions in line with evidence-based practice. Changes in staff cognitive representation of challenging behaviour, as a result of training may be multi-dimensional.