Two-Level rules are declarative constraints that describe morphological alternations, such as the y ie alternation in the plural of some English nouns (spy spies). This document describes a compiler, written in C, that converts two-level rules into deterministic, minimized finite-state transducers. It describes the format of two-level grammars, the rule formalism, and the user interface to the compiler. It also explains how the compiler can assist the user in the development of a two-level grammar.