Previous research demonstrates that identity affirmation is associated with greater well-being and increased intentions to engage in collective actions among minority individuals. However, these studies typically involve the affirmation of a single identity. Little is known about whether affirming multiple identities, compared to a single identity, might yield additional benefits. In a Registered Report experiment with a sample of N = 401 LGB-religious individuals, we tested the effect of a dual- vs. single-identity affirmation intervention on well-being and collective action intentions, and whether these effects depend on individuals’ identity integration. Participants completed an identity-integration scale and were randomly assigned to one of four conditions: dual-, single-religious-, single-sexual-identity affirmation, or a control condition. Well-being and collective action intentions were then measured. Identity affirmation interventions (vs. control) increased well-being. Identity integration was also positively associated with all outcomes. However, we found mixed results regarding the interaction between identity affirmation and identity integration. Contrary to expectations, dual-identity affirmation was not especially effective for individuals high in identity integration. Instead, dual-identity affirmation increased collective action intentions primarily among individuals low in identity integration. We discuss how dual-identity affirmation may help reconcile conflicting identities and foster collective action, particularly among individuals experiencing identity conflict.