Specific developmental disorders of speech, language, and motor function in children are associated with a wide range of mental health problems. We examined whether preschool-age psychiatric patients with specific developmental disorders and those without differed in the severity of emotional and behavior problems. In addition, we examined whether the 2 groups differentially benefited from child psychiatric family day hospital treatment. Data from (N = 78) preschool-age boys (27 with a developmental disorder and 51 without) were analyzed. Before and after treatment, child emotional and behavior problems were rated by parents on the German version of the Child Behavior Checklist for Ages 1.5-5 (T. M. Achenbach & L. A. Rescorla, 2000; Arbeitsgruppe Deutsche Child Behavior Checklist, 2002) and by therapists on the German version of the Caregiver-Teacher Report Form for Ages 1.5-5 (T. M. Achenbach & L. A. Rescorla, 2000; Arbeitsgruppe Deutsche Child Behavior Checklist, 2002). Results indicated small-to-moderate differences between groups in the severity of specific emotional and behavior problems, and there were hints that children without developmental disorders benefited more from treatment than those with developmental disorders. However, results depended clearly on the perspective of the informant, with mothers generally perceiving more treatment benefit and less group differences than therapists. Child psychiatric patients with additional developmental disorders differ slightly from children without additional developmental disorders in the severity of emotional and behavior problems. The evaluation of treatment appears to be more strongly influenced by the informant's perspective than by pretreatment group differences. Reasons for informant differences, especially the observed maternal optimism, may include treatment-related changes in maternal mood, increased parenting skills, and improvement of the mother-child interaction.