The Reading the Mind in the Eyes Test (RMET) is a purported theory of mind measure and one that reliably differentiates autistic and non-autistic individuals. However, concerns have been raised about the validity of the measure, with some researchers suggesting that the multiple-choice format of the RMET makes it susceptible to the undue influence of compensatory strategies and verbal ability. We compared the performance of autistic (N = 70) and non-autistic (N = 71) adults on the 10-item multiple-choice RMET to that of a free-report version of the RMET. Both the autistic and non-autistic groups performed much better on the multiple-choice than the free-report RMET, suggesting that the multiple-choice format enables the use of additional strategies. Although verbal IQ was correlated with both multiple-choice and free-report RMET performance, controlling for verbal IQ did not undermine the ability of either version to discriminate autistic and non-autistic participants. Both RMET formats also demonstrated convergent validity with a well-validated adult measure of theory of mind. The multiple-choice RMET is, however, much simpler to administer and score.