externalizing problems, though the specific behaviors may morph to more appropriately reflect the present developmental period (Kagan, 1969; Kagan & Moss, 1983). Two studies examining adolescents within non-selected samples of European Americans have found distinct subgroups exhibiting persistently elevated levels of risk in relation to a variety of disinhibitory behaviors including physical aggression (4%; Nagin & Tremblay, 1999), opposition (~6%; Bongers et al., 2004; Nagin & Tremblay, 1999), property violations (5%; Bongers et al., 2004), and even hyperactivity (6%; Nagin & Tremblay, 1999). Thus, the trajectories found in this sample appear to be representative of those described in the extant literature on discrete patterns of development across a broad range of conduct problems.
