Eleven residential care staff working in a secure unit with disruptive or delinquent youths were trained to use a variety of behavioural methods and teaching-parent interaction skills as outlined by the Achievement Place Programme. Three months following a 1-month full-time training programme, staff were observed in the work environment using a behaviour coding system. An attempt was made to identify which care staff behaviours influenced the clients and colleagues judgements about staff behaviour towards the youths. Staff who frequently asked for information from the youths were rated more positively by both colleagues and youths. The use of praise influenced the youths judgements of care staff, whereas the expression of affection towards the youths influenced staff judgements of colleagues. Other aspects of conversation or teaching interaction skills did not correlate with boys or colleagues judgements of the care staff. Responses such as checking for understanding, requesting practice, giving prompts and feedback were rarely used by care staff. The study provides evidence of social validity for certain staff behaviours as influencing judgements made by clients and colleagues.