Understanding how a child acquires his or her native tongue is one of the major unsolved mysteries of psychology. Categories and Processes in Language Acquisition, originally published in 1988, and as the title indicates is about the acquisition of linguistic categories, and about the child’s learning processes. The categories of concern are those that are manifest in structure, i.e., other than simply as word meanings. The book begins with a chapter on the earliest nonlexical categories for which there is evidence. Then there are several chapters on word classes and the acquisition of relational categories, followed by papers that discuss models of the child’s learning mechanism. Finally, there is an integrative concluding chapter by two of the editors. Today it can be read in its historical context.