There are well-known correlations between low cognitive ability and support of prejudicial or non-egalitarian attitudes. This paper adds to existing knowledge by providing the first analyses of the associations between cognitive ability and attitudes towards LGBT issues in a non-US sample (Australia), comparing these across three measures of cognitive ability, and examining the separate, joint and interactive effects of education and cognitive ability. Findings from a high-quality, national Australian dataset (n = 11,564) indicate that individuals with low cognitive ability are less likely to support equal rights for same-sex couples. This pattern holds in the presence of confounds, is consistent across measures of ability, and is more pronounced for verbal ability. Education and cognitive ability affect attitudes through similar channels, but retain independent effects.