Legislative and cultural changes have produced significant shifts in sexual and gender rights. Although this has been extensively studied in relation to those who have “won” and in relation to the normalisations that these changes create, there is little scholarship on the emergence of new resistances to Lesbian, Gay, Bisexual and Trans equalities. We employ the term heteroactivism to name the ways that resistances to sexual and gender rights have moved from vilifying “the homosexual,” towards more subtle and nuanced resistances in places with sexual and gender equalities legislation. Geography is key because legislation and its enactment varies spatially, and national legislations and imaginings recreate distinctive, place-based heteroactivism. Paying attention to the ideologies of those who opposed same-sex marriage in Ireland’s 2015 referendum, this paper explores how the boundaries of Irishness were central to heteroactivist campaigns, drawing on specific invocations of relatedness between a female child and her mother, the quintessential Irish Mammy. Using a close reading of the textual and visual elements of a “Vote No” poster, the paper elucidates the presences and silences of new forms of resistances that seek to recuperate what was once not only “common sense” heterosexuality, but also seen as the essence of Irishness. In doing so, the paper extends understandings of sexuality–gender–nation–state nexus by critically interrogating the ideologies of those who contest progressive state sexual and gender legislation.