Abstract: By focusing on the legislative process underpinning marriage equality in the American states, this article identifies the combinations of conditions under which attempts at institutional displacement succeed or fail. Hitherto, few scholarly works have empirically examined displacement and whether, and how, actors can preserve institutional stability in the face of organized efforts to change institutions. Taking causal complexity into account, the analytical model factors in the resources of both change and status quo actors as well as the political context that enables or constrains their strategies. The results of the comparative analysis show that states have followed different paths to the displacement of heterosexual marriage in favor of marriage equality. Yet, most crucially, the findings pinpoint that the inclusion of religious exemption clauses is a condition sine qua non for marriage equality laws to be effectively passed, thus challenging the widely accepted notion that morality policies are foreign to compromise.