ABSTRACT. Objective: When asked about substance use, youths typically endorse higher levels of use than parents, suggesting that parents are often unaware of their child's drug and alcohol use. This study sought to examine the level of concordance between reports of youths enrolled in public sectors of care and their parents, and identify potential predictors of parental awareness of substance use and related problems. Method: Youths receiving services in one or more public sectors of care (N = 985; 67% male) and their parents were interviewed about the youths' substance use and substance use problems, as well as associated demographic, parental, and youth factors. Results: As has been found in other studies, youths generally reported higher rates of substance use and substance use problems compared with parents. Rates of agreement ranged from κ = .24 (sedatives) to κ = .67 (marijuana) and were higher for drug problems (κ = .47) than for alcohol problems (κ = .34). Predictors of parental awareness of drug problems included youth gender (male), race (White compared with Hispanic), and higher ratings of youth's functional impairment. Predictors of parental awareness of alcohol problems included race (White compared with Hispanic), lower levels of youth-reported parental monitoring, lower levels of parental depression, and higher ratings of youth functional impairment. Conclusions: In this high-risk population, a signifi cant proportion of parents are unaware of their child's alcohol (30%) and substance use (50%) problems. Services geared toward enhancing parental awareness, especially for parents of Hispanic and female youths, may increase communication and treatment seeking. (J. Stud. Alcohol Drugs, 72,