Societies are becoming more polarised, driven in part by misconceptions about out-groups’ beliefs. To understand these effects, one must examine the cognitive processes underlying how people think about others. Here, we investigate whether people are less prone to theorise about the minds of out-groups, or less able to do so. Participants (Study 1: n = 128; Study 2: n = 128) made inferences about social and political beliefs held by real in-group and out-group members, and could choose to receive further information to improve these inferences. Results show: (1) participants sought equivalent or greater information about out-groups relative to in-groups; but despite this, (2) made significantly less accurate inferences for out-groups; and (3) were significantly less aware of their reduced ability. This shows that poorer mental state inference is not underpinned by a reduced propensity to consider out-group minds, but instead by a worse representation of the minds of out-groups.