This study investigated the relationships of metal levels and metal combinations to children's classroom behavior. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 80 randomly selected elementary-age children, who were also rated by their classroom teacher on the Walker Problem Behavior Identification Checklist (WPBIC). Parents were interviewed to control for confounding variables that may have affected behavioral development. Regression analysis indicated that the set of metals was significantly related to increased scores on four of the five WPBIC subscales and on the total scale, with lead being a major contributor to four of the six dependent measures. Metal combinations were significantly related to increased scores on the WPBIC subscales measuring acting-out, disturbed peer relations, and immaturity, and on the total scale. A continuing reexamination of metal poisoning concentrations is needed because metal levels and metal combinations previously thought harmless may be associated with nonadaptive classroom behavior.