This chapter considers the relationship between antitrust law and the First Amendment as those topics relate to workers’ collective action. It asks why the US Supreme Court has remained unwilling to accept First Amendment defenses in cases involving potential antitrust liability for strikes and boycotts, even as it has expanded the scope of First Amendment protections available in analogous situations. The chapter begins by reviewing foundational cases regarding antitrust liability for strikes and boycotts. It then discusses subsequent developments in First Amendment doctrine related to commercial speech, free association, and civil-rights boycotts. Finally, the chapter turns to the 1990 US Supreme Court case, Federal Trade Commission v. Superior Court Trial Lawyers Association, showing how First Amendment principles that are uncontroversial in other contexts could have driven a different outcome. The chapter closes with observations about the modern Supreme Court’s views of the purposes of the First Amendment, and difficulties workers and unions are likely to encounter thereunder.