Intergroup contact is considered one of the most effective ways to reduce prejudice. An extension of contact theory, the secondary transfer effect (STE), stipulates that contact with a primary outgroup can impact attitudes toward a second, uninvolved outgroup. Here, we test the direct and indirect effects of contact with the primary outgroup on attitudes toward the secondary outgroup through outgroup humanisation, assessing White, heterosexual Americans' contact with both Black and gay people (N = 471; 52.7% men; Mage = 44.90, SD = 14.75). Path analyses were conducted on four fully saturated models that included intergroup contact (quantity, quality), humanisation of each group, and intergroup outcomes (attitudes, collective action intentions). Direct generalisation consistently occurred from gay contact (quantity or quality) to Black attitudes or Black collective action. Only one indirect generalisation pathway consistently occurred: a greater quantity of gay contact humanised Black people, which itself was associated with more positive attitudes and stronger collective action intentions toward Black people. However, the converse generalisation was not found: Black contact was rarely associated with direct or indirect intergroup outcomes toward gay people. The present study is the first to find indirect humanisation pathways for the STE, but from gay‐to‐Black contact only. Implications for future research are discussed. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.