Work is currently underway on the fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). Each new version of the manual reflects, in part, the progress in the understanding of psychopathology that has been accomplished since the previous version. This special section gathers summaries of several relevant advances of particular relevance for the Diagnostic and Statistical Manual of Mental Disorders revision process and, more generally, for any effort to describe psychopathology in valid and useful ways. Recent advances in the description of psychopathology have been dramatic, and there is an emerging consensus that fundamental changes to the diagnostic process are necessary to capture the validity and the utility of the description that is currently available in the field. The articles in this special section play 2 roles: They describe the fundamental changes that are necessary, and they provide a stepping stone for the next wave of advances in psychological assessment research.