Using the U.S. Supreme Court’s 2015 opinion in Williams-Yulee v. Florida Bar as an analytical springboard, this Article examines the slipperiness—and sometimes fatalness—of the underinclusiveness doctrine in First Amendment free-speech jurisprudence. The doctrine allows lawmakers, at least in some instances, to take incremental, step-by-step measures to address harms caused by speech, rather than requiring an all-out, blanket-coverage approach. Yet, if the legislative tack taken is too small to ameliorate the harm that animates a state’s alleged regulatory interest, it could doom the statute for failing to directly advance it. In brief, the doctrine of underinclusivity requires lawmakers to thread a very fine needle’s eye between too little and too much regulation when drafting statutes. This Article argues that while Williams-Yulee attempts to better define underinclusivity, its subjectivity remains problematic.