We hypothesise on a number of grounds that the personality dimension of Agreeableness may be associated with inter-individual differences in theory of mind (ToM) functioning. However, it is important to distinguish social-perceptual from social-cognitive ToM. Previous findings on ToM in psychopathic individuals, sex differences in ToM and the associations between ToM and social relationships, all suggest that social-cognitive ToM is more likely than social-perceptual ToM to relate to Agreeableness. In separate empirical studies, we find that Agreeableness is substantially correlated with social-cognitive ToM performance, but uncorrelated with social-perceptual ToM performance. We suggest that the propensity or motivation to attend to the mental states of others may be central to the personality dimension of Agreeableness. Copyright © 2008 John Wiley & Sons, Ltd.