Past research has assumed that social egalitarians reject group-based hierarchies and advocate for equal treatment of all groups. However, contrary to popular belief, we argue that egalitarian advocacy predicts greater likelihood to support “succession”-based ageism, which prescribes that older adults step aside to free up coveted opportunities (e.g., by retiring). Although facing their own forms of discrimination, older individuals are perceived as blocking younger people, and other unrepresented groups, from opportunities — that in turn, motivates egalitarian advocates to actively discriminate against older adults. In 9 separate studies (N = 3,277), we demonstrate that egalitarian advocates endorse less prejudice toward, and show more support for, women and racial minorities, but harbor more prejudice toward (Studies 1 and 2), and show less advocacy for (Studies 3–6), older individuals. We demonstrate downstream consequences of this effect, such as support for, and resource allocation to, diversity initiatives (Studies 3–6). Further, we isolate perceived opportunity blocking as a critical mediator, demonstrating that egalitarian advocates believe that older individuals actively obstruct more deserving groups from receiving necessary resources and support to get ahead (Studies 4–6). Finally, we explore the intersectional nature of this effect (Study 7). Together this research suggests that when it comes to egalitarianism, equality for all may only mean equality for some.