Based on an instance of "clinical lore" we assess the efficacy of children's and adolescents' knowledge of family history as an index of psychological well-being and potential for positive change in clinical and educational settings. We report that knowledge of family history is significantly correlated with internal locus of control, higher self-esteem, better family functioning, greater family cohesiveness, lower levels of anxiety, and lower incidence of behavior problems. We suggest that through the use of a brief measure of family knowledge, practicing clinicians can rapidly generate a data-based correlate of children's well-being and likelihood of overcoming psychological and educational challenges. (PsycINFO Database Record (c) 2010 APA, all rights reserved).