AbstractWe evaluate the importance of callous‐unemotional (CU) traits as a personality construct in isolation from other facets of psychopathy. Specifically, we review research suggesting that these traits are useful for designating a subgroup of youth with serious conduct problems who differ from other antisocial youth on important biological, emotional, cognitive, and social characteristics. In addition, the temperamental features related to CU traits are risk factors for impairments in conscience development in young children. Thus, these traits could advance theoretical models explaining the development of severe antisocial behavior and psychopathy. CU traits also have important clinical utility because they designate a particularly severe and impaired subgroup of antisocial youth, leading to their inclusion in the DSM‐5. As a result of this inclusion in diagnostic classification, there has been an increased focus on how to best assess CU traits, and we discuss several key issues in their assessment, highlighting several limitations in existing measures. Finally, the increased use of CU traits, separately from other facets of psychopathy, makes it important to determine how these traits relate to other personality constructs. Thus, we examine how measures of CU traits relate to the broader construct of psychopathy and to other basic personality dimensions.