Background: Most researchers agree that autistic children suffer from socio-pragmatic dysfunctioning. Their difficulties to use behaviors in socially meaningful ways may give rise to structural-functional incongruities affecting their "psychological" relation to their partners. This paper investigates autistic children's functioning in this domain by studying their communicative behavior in familiar naturally-occurring interactional settings, a context that still remains understudied. Objectives: Compare the pragmatic functioning of 6 moderately retarded autistic children (chronological age: 5;11 to 9;11 years) and of their familiar partners to that of 9 typically developing children (chronological age:2 to 6;6 yrs) and of their partners, during naturally-occurring "oppositional" episodes (protests, refusals and denials). Methods: Autistic children, diagnosed by experienced clinicians (DSMI-IV and ADI-R), were matched to controls on the receptive part of a vocabulary test (the TVAP)). For each family, the data analysed consist in 2 sessions of 30 minutes each, videorecorded at home. Oppositional episodes, including justifications, insistence and acceptance, were systematically coded according to well defined criteria (inter-rater reliability : .85). Results: Compared to controls matched on verbal age, less advanced autistic children (Verbal age: 3-4 yrs) produce less justifications. More advanced autistic children (Verbal age: 6-7 yrs) do not differ quantitatively from controls but their justifications are less effective in persuading their partners. Furthermore, these children do not seem to be immediately persuaded by the justifications offered by their partners. Autistic children's familiar partners justify as much as controls their oppositional moves, but are not persuaded right away by the justifications of their children. Contestation of justifications and counter-arguing seems to be a possible cause. Conclusion: Findings support the existence of similarities and differences in the pragmatic functioning of autistic children and of their familiar partners compared to verbal age matched controls. Specific difficulties reside in the expression of autistic children's own communicative intentions and in their difficulties in attributing communicative intents to their partners (difficulties in implicit ”theory of mind”).