Formalism in contract law has had many defenders and many critics. What lawmakers need, however, is an account of when formalist approaches work and when they do not. This article addresses that need by providing general theory of the rules of contract interpretation and construction and identifying several ways those rules can be more or less formalist. The theory draws from legal philosophy, the philosophy of language, economic contracts scholarship, and caselaw. The result is a distinction between two forms of formalism in contract law. Formalities effect legal change by virtue of their form alone, thereby obviating interpretation. Examples from contract law include “as is”, the seal, and some contract boilerplate. Evidentiary formalism,...