The concept and measurement of psychopathy in young people is discussed with respect to five key issues: (1) the respective merits of self-reports and ratings by others; (2) whether callous/unemotional (CU) features may be more appropriately tapped by physiological measures; (3) the possible utility of genetic studies; (4) the distinctiveness of CU from other risk factors for antisocial behavior; and (5) the homogeneity of CU as a construct.