Abstract: Both within the Supreme Court and among scholarly commentators, a debate rages about when litigants should be able to challenge statutes as "facially" invalid, rather than merely invalid "as applied." To a large extent, this debate reflects mistaken assumptions. There is no single distinctive category of facial, as opposed to as-applied, litigation. All challenges to statutes arise when a litigant claims that a statute cannot be enforced against her. In the course of as-applied litigation, rulings of facial invalidity sometimes occur, but they do not reflect trans-substantive rules governing a purported general category of facial challenges. Rather, rulings that a statute is facially (or partly) invalid are the consequence of the particular doctrinal tests applied to resolve particular cases. Some doctrinal tests call for statutes to be tested on their faces, whereas others do not. Accordingly, debates about the permissibility of facial challenges should be re-cast as debates about the substantive tests that should be applied to enforce particular constitutional provisions. Third-party standing rules introduce a further element of plurality into the forms of constitutional adjudication. The resulting doctrinal structure is diverse, but probably no more so than are the rights that constitutional litigation seeks to vindicate.