The process of documenting and describing the world's languages is undergoing radical transformation with the rapid uptake of new digital technologies for capture, storage, annotation and dissemination. However, uncritical adoption of new tools and technologies is leading to resources that are difficult to reuse and which are less portable than the conventional printed resources they replace. We begin by reviewing current uses of software tools and digital technologies for language documentation and description. This sheds light on how digital language documentation and description are created and managed, leading to an analysis of seven portability problems under the following headings: content, format, discovery, access, citation, preservation and rights. After characterizing each problem we provide a series of value statements, and this provides the framework for a broad range of best practice recommendations.