Theories that propose a modular basis for developing a “theory of mind” have no problem accommodating social interaction or social environment factors into either the learning process, or into the genotypes underlying the growth of the neurocognitive modules. Instead, they can offer models which constrain and hence explain the mechanisms through which variations in social interaction affect development. Cognitive models of both competence and performance are critical to evaluating the basis of correlations between variations in social interaction and performance on mental state reasoning tasks.