Theory of mind, also called mindreading or mentalizing, is the ability to ascribe mental states to oneself and others in order to explain, predict and manipulate behaviour. A large number of developmental studies have focused on mindreading and how it emerges throughout infancy and childhood, but relatively few have focused on individual differences in adulthood, and potential modulators of this capacity. One important possible modulator is culture. People from other cultural backgrounds sometimes seem inscrutable. Investigating how cultural information affects adults’ mindreading reasoning may therefore shed new insights on this process. The main aim of the present thesis was to find out whether complex mental state attribution and its response times are modulated by cultural information about the target. In order to answer these questions, we carried out two experiments in which culturally adapted versions of the Strange Stories task (White, Hill, Happé & Frith, 2009) were administered to participants of the same or a different cultural background. Specifically, in Experiment 1, Australian participants were randomly allocated to one of two conditions. In the Australian condition, names, pictures, places and objects were adapted to match to an Australian context, in the Cross-cultural condition the Australian participants were shown targets belonging to different cultural backgrounds. Results showed that participants gave faster and more accurate mindreading responses for targets that matched their cultural background, relative to cross-cultural targets. Experiment 2 was similar to Experiment 1, but with two main modifications: (1) Australian participants were presented with Strange Stories that depicted a single (as opposed to multiple) different cultural backgrounds (namely, Chile) and (2) a Chilean sample was also recruited, and asked to complete intra- and Australian versions of the Strange Stories task. As in Experiment 1, for both Australian and Chilean samples, accuracy was higher in the intracultural relative to the cross-cultural mentalizing conditions. There was also some evidence for increased reaction time in the intracultural condition, but this was only significant for one of the two cultural groups. Taken together, these results provide evidence for differential cultural effects on mindreading reasoning. These data therefore contribute to ongoing debate about whether mindreading ability differs in our day-to-day social interactions with people thatbelong to different cultural backgrounds, with potentially important implications for cross-cultural communication and understanding.