BACKGROUND: A dominant idea is that impaired capacities for theory of mind (ToM) are the reasons for impairments in social functioning in several conditions, including autism and schizophrenia. In this paper, we present empirical evidence that challenges this influential assumption. METHODS: We conducted three studies examining the association between ToM and social functioning in participants diagnosed with a non-affective psychotic disorder and healthy individuals. We used both the experience sampling method, a structured diary technique collecting information in daily-life, and a standardised questionnaire to assess social functioning. Analysed data are part of Wave 1 and Wave 3 of the Genetic Risk and Outcome of Psychosis (GROUP) study. RESULTS: Results were highly consistent across studies and showed no significant association between the two constructs. CONCLUSIONS: These findings question the leading assumption that social cognition is a prerequisite for social functioning, but rather suggest that social cognition is possibly a result of basic social interactive capacities.