Two studies examined the understanding and self-reported use of rules for the expressive display of emotions in children with high functioning autism spectrum disorders (HFASD) and in typically developing children. In Study 1, children from the two groups reported display rules equally often when presented with hypothetical situations that provided clear motives for using display rules, although emotion-masking displays were more commonly identified for vignettes with prosocial rather than self-protective motives. In Study 2, children were interviewed about display rule use in real life. Children with HFASD reported display rules less often, included more prototypical examples, and referred less often to prosocial motives than typically developing children. Children with HFASD appear to be aware of display rules, but are less adept at identifying the interpersonal functions of such rules than their typically developing peers. © 2010 Psychology Press.