This Review makes two claims. The first is that Paul Horwitz’s excellent book, "First Amendment Institutions," depicts the institutionalist movement in robust and provocative form. The second is that it would be a mistake to assume from its immersion in First Amendment jurisprudence (not to mention its title) that the book's implications are limited to the First Amendment. Professor Horwitz presents First Amendment institutionalism as a wide-ranging theory of constitutional structure whose focus is as much on constraining the authority of political government as it is on facilitating expression. These are the terms on which the book's argument — and, to a large extent, the leading edge of contemporary institutionalist thinking — ought to be received, understood, and evaluated.