Many pediatricians use a broad developmental screening test as part of well-child care, but do not specifically screen for behavioral and emotional disorders. Parents at 2 urban community agencies completed both the Ages and Stages Questionnaire (ASQ-3) and the Ages and Stages Questionnaire: Social Emotional (ASQ:SE) for 608 children, ages 2 to 60 months; 51.8% in Spanish. Less than half of the children with a positive screen on the ASQ:SE would have been identified as needing additional assessment or intervention if only the ASQ-3 had been administered. Younger children with positive ASQ:SE screens were significantly less likely to be referred for mental health services compared with older children. Physicians should consider screening all young children for social-emotional and behavioral needs, and referring those identified for infant and early childhood mental health services.