Compulsivity and impulsivity are cross-cutting, dimensional symptom domains that span traditional diagnostic boundaries. We examine compulsivity and impulsivity from several perspectives and present implications for these symptom domains as they relate to classification. We describe compulsivity and impulsivity as general concepts, from the perspectives of the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) Research Planning Agenda, and from the DSM-5 workgroups, literature reviews, and field trials. Finally, we detail alternative modes of classification for compulsivity and impulsivity in line with the Research Domain Criteria (RDoC) and International Classification of Diseases (ICD-11).