Computer-mediated communication in individuals with Asperger syndrome, Tourette syndrome and normal controls was explored with a program called Bubble Dialogue (Gray, Creighton, McMahon, & Cunninghamn (1991)) in which the users type text into speech bubbles. Two scenarios, based on Happe (1994) were adapted to investigate understanding of figure of speech and sarcasm, and a third, developed by ourselves, looked at responses to inappropriate requests (lending money and disclosing home address on a first meeting). Dialogue transcripts were assessed by 62 raters who were blind to the clinical diagnoses. Hierarchical linear modelling revealed that rated understanding of a figure of speech was predicted mainly by verbal ability and executive ability, as well as by clinical diagnosis, whereas handling inappropriate requests was predicted by age, verbal ability, executive ability and diagnosis. Notably, the Tourette comparison group showed better understanding than the Asperger group in interpreting a figure of speech and handling inappropriate requests, and differences between these groups were possibly attributable to individual differences in executive ability. In contrast, understanding sarcasm was predicted by age but not by either verbal ability, executive ability or clinical diagnosis. Evidently, there is a complicated relation between Asperger syndrome, verbal ability and executive abilities with respect to communicative performance.