This handbook develops a methodology for writing and testing wide coverage, maintainable grammars. Parallel grammars for English, French, and German using Lexical Functional Grammar (LFG) as a framework are used as an example. Parallel grammars are grammars with similar coverage in different languages which explore how similarly one can treat various phenomena cross-linguistically. This issue of the parallelism of the analyses is a central concern in maximizing portability and extendability of the analyses to other grammars and languages. For the grammar writer, this handbook provides a useful guide to the range of constructions to be considered in a wide-coverage grammar and the theoretical and practical issues which their implementation gives rise to. The interaction between theory and implementation is discussed, including the implementation of new theoretical developments in LFG such as coordination via distribution, functional uncertainty, and a featural analysis of auxiliaries.