Communicative dysfunctions in autism are often attributed to impaired Theory of Mind (ToM). However, very few studies investigate autistic children's communicative engagements in ecologically valid and socially meaningful contexts. This paper focuses on oppositional episodes occurring in everyday family life. These episodes, clearly identifiable and very frequent in familiar settings, are particularly demanding in communicative adaptation. Within a socio-cognitive and pragmatic approach to communication, we argue that the way children and their partners negotiate oppositional episodes, and in particular how they provide and deal with justifications, reveals children's level of 'ToM in action'. The study compares 10 children with autism (5 to 11 yrs) to 15 typically developing children (2 to 8 yrs), 10 matched on verbal age and 5 younger. All children were videotaped at home during spontaneous interactions with familiar partners. The data analyzed consist in an hour of interaction per family, filmed during meal and play contexts. All naturally-occurring oppositional episodes (protests, refusals and denials) were coded exhaustively according to well defined criteria (inter-rater reliability: .85), noting in particular justifications and manners of insistence or acceptance, until the explicit or implicit resolution of the episode. On this basis, four specific measures of communicative functioning were elaborated. Results show differences but also resemblances among groups and verbal-age levels. In particular, in families with a verbally advanced autistic child, both children's and partners' justifications are less persuasive than in verbally-matched control families. The measures of pragmatic functioning are examined for their relevance to communication and ToM's understanding by autistic children. .