In the wake of Burwell v. Hobby Lobby, religious accommodation has become increasingly controversial. That controversy has given rise to a new legal theory gaining popularity among academics and possibly a few Supreme Court justices: the idea that the First Amendment's Establishment Clause condemns accommodations whenever they generate anything beyond a minimal cost for third parties.The third-party thesis is appealing. But this Article argues that there are good reasons to believe it falls short as an interpretation of the Establishment Clause. In its place, the Article offers a new theory for understanding the relationship between costly accommodations and the Establishment Clause. That theory begins with a simple assertion: the Establishment Clause is not a prohibition on generic harm but instead a ban on government attempts to promote a favored religion. Thus, the fundamental inquiry is not whether a private party bears some cost but instead whether the government is using its power to foster religious conformity.Although largely overlooked in the literature, members of the founding generation actually did equate accommodations with establishments on at least two occasions, both involving instances in which accommodations encouraged religious conformity. And as it turns out, the principles drawn from those incidents provide powerful explanations for many of the Court’s modern precedents—sometimes more powerful than the Court’s own reasoning. But even more, viewing the Establishment Clause as a ban on attempts to induce religious conformity also offers a more plausible way of thinking about the occasional costs of accommodation. This approach will be more more deferential to legislative judgments than an approach focused squarely on harm. But that is not a reason for rejecting it, especially when the limits it provides have proven fairly reliable in dealing with the problem.