A variety of cognitive diagnosis approaches (CDAs) have been used by researchers to extract fine-grained information about the linguistic knowledge states and skill mastery levels of test takers based on their performance on language tests. Although some of these approaches have been in use in the psychometric community for quite some time, many of these are relatively new to language testers and have not been widely researched or discussed in the field. The goal of this article is to describe how a CDA framework could be applied to language assessment. We start with a brief history and an overview of the major components of CDAs and then compare the characteristics of psychometric models for CDAs and discuss score interpretation and reporting issues. We conclude this article by outlining some of the challenges ahead and future research avenues for the application of CDAs in language assessment. (Contains 3 tables and 1 figure.)