This pilot investigation evaluated the effectiveness of siblings as generalisation agents in an 8-week social skills training (SST) program designed for boys with Asperger syndrome (AS). Twenty-one boys aged 8-12 participated in a SST group alone, with a sibling, or remained in a wait-list control group. After training, participants' identification of non-verbal social cues significantly improved and was maintained at 3-month follow-up, irrespective of sibling involvement. Similar trends existed for participants' ability to accurately interpret emotions relative to controls. Improvements did not extend to parent and teacher ratings on standardised social skills measures, suggesting poor generalisation, or questionable sensitivity of measures to taught skills. Results suggest some promise in improving social skills training for children with AS. (Contains 1 table and 4 figures.)