Social workers should benefit from reliable and valid measures of both substance abuse and antisocial behaviors among adolescents. Perhaps the most compelling reason for such measures is simply that social workers are likely to encounter adolescents with these problems. Findings from large scale epidemiological studies have shown that these two conditions are among the most common mental health problems experienced by youth (Armstrong and Costello, 2002; Kandel et al., 1999). Furthermore, substance abusers are frequently involved in various publicly funded social service settings where social workers are likely to be employed (Aarons, Brown, Hough, Garland, and Wood, 2001). Thus, selecting appropriate measures to assess substance abuse and antisocial behaviors is of particular importance in the field of social work.