Callous-unemotional tendencies, which include restrained empathy, a loss of guilt, and shallow affect have received increased interest from each researchers and clinicians in recent years. Paul Frick trail-blazed research on this place via operationalizing a developmentally touchy measure to seize such tendencies in children. Over the years, work through an impressive collective of colleagues, which include Frick, on the University of New Orleans; James Blair, on the National Institute of Mental Health; Don Lynam, at Purdue University; Adelle Forth, at Carleton University, Canada; Dustin Pardini, at the University of Pittsburgh; and Mark Dadds, on the University of New South Wales, Australia, have employed lots of methodologies to convincingly show that callous-unemotional trends delineate a set of teens at threat for intense and violent delinquent behavior that regularly persists into adulthood. These traits are also associated with increased danger of adult psychopathy. The Inventory of Callous-Unemotional Traits (ICU) is a copyright blanketed 24-item questionnaire designed to provide a comprehensive evaluation of callous and unemotional developments. These tendencies have confirmed to be critical for designating a wonderful subgroup organization of delinquent and aggressive young people. The ICU has three subscales: Callousness, Uncaring, and Unemotional. Contemporary definitions of psychopathy in adults embody ratings of each affective disorder and overt antisocial conduct. The affective disorder side of psychopathy includes reduced guilt and empathy, in addition to reduced attachment to sizable others. In kids, these functions were variously termed “callous–unemotional” (CU) developments, “psychopathic developments,” and, most recently, within the fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), “limited prosocial emotions”; in this chapter, we use the term “CU tendencies” for consistency. Cleckley viewed this affective dysfunction as the “hallmark” of psychopathy, with Bowlby’s next description of “affectionless psychopathy” constituting the first extension of the psychopathy idea to children. In this chapter, we first provide a top level view of approaches to assessing the “callous–unemotional” (CU) construct, as its operationalization always influences research questions and participant samples centered for take a look at. Second, we review proof regarding the temporal balance of CU tendencies. Third, we offer a brief evaluation of studies that has investigated whether CU developments symbolize an etiologically distinct subgroup of kids with antisocial behavior, focusing in particular on genetic threat research and neurocognitive and experimental work. Despite thrilling advances yielded with the aid of studies across these specific stages of analysis, the field remains a long manner from a nuanced, multilevel, developmentally informed know-how of CU tendencies and psychopathic behavior. Accordingly, we discuss both the promise of the extant evidence base and its limitations, and do not forget some of issues relevant to the study of CU developments, longitudinally and throughout tiers of analysis. Finally, we offer some tips for future studies efforts on this vicinity.