A randomized controlled trial was used to evaluate a parent training intervention for caregivers with preschool-age children with developmental disabilities. The 21 families in the experimental group received usual care plus the 12-week Incredible Years Parent Training Program with developmental delay modifications. Families in the control group (n = 23) received usual care, including early childhood education and related services. Results suggest that this parent training intervention was superior to usual care for young children with developmental delays or disabilities in reducing negative parent-child interactions and child behavior problems. Participants in the experimental group indicated high satisfaction with treatment. Additional research is necessary to document maintenance and generalization of treatment outcomes.Children and adults with intellectual and other developmental disabilities are more likely to be diagnosed with a severe behavior disorder or mental health diagnosis than are their typically developing counterparts (Emerson, 2003). This dual diagnosis of cognitive and behavioral impairments places additional strain on parents and teachers (Baker et al., 2003;McIntyre, Blacher, & Baker, 2006) and may be overlooked or underreported by health care providers (Levitan & Reiss, 1983). Furthermore, children with developmental disabilities and behavior or mental health disorders are at greater risk for difficulties in school; are more likely to be placed in out-of-home residential care; and, as adults, are more likely to have problems in the workplace (Borthwick-Duffy & Eyman, 1990;McIntyre, Blacher, & Baker, 2002;Taanila, Ebeling, Heikura, & Järvelin, 2003).Although estimates of mental health problems in children and adolescents with developmental disabilities vary depending on sampling procedures, diagnostic criteria, and age of individual, estimates are generally thought to be between 25% to 40% (Emerson, 2003). Emerson, for example, conducted a prevalence study of psychiatric disorders in 10,438 children in the United Kingdom. Children with intellectual disability were seven times more likely to have a psychiatric disorder than children with no intellectual disabilities (Emerson, 2003). Because of the negative impact that behavior problems place on caregivers, some have suggested the need for early intervention for children and families most at risk . Few researchers, however, have employed rigorous methods in treatment evaluations for families and children with developmental disabilities. One treatment option, often used with children without developmental disabilities, is parent training.Given the established link between parenting practices and children's behavior (e.g., Hinshaw, 2002;Patterson, 1976;Sameroff & Fiese, 2000), parent training has been employed to alter (Webster-Stratton, 2001). Floyd, Harter, and Costigan (2004) found that negative parent-child interactions during family problem-solving was associated with child behavior problems in children with intellectual disability...