In regard to mental health impairment, disruptive behavior has been found to be the most frequent cause of child outpatient or inpatient referral (Wells & Forehand, 1985) and is estimated to affect up to 23% of children (O'Brien, 1996). In addition to an especially poor prognosis, the societal cost of children with disruptive behavior disorders (DBD) is great. Estimates indicate that a child with severe behavioral problems is about ten times more expensive than a child without such problems (Scott, Knapp, Henderson, & Maughan, 2001). Given the potential monetary benefits of early among this population, as well as the intangible gains associated with improved behavior and a safer community, it is advantageous to explore DBD treatments that are efficacious and financially prudent. The current paper sets out to evaluate the cost-effectiveness of Parent-Child Interaction Therapy (PCIT; Eyberg, Boggs, & Algina, 1995; Hembree-Kigin & McNeil, 1995), an empirically supported treatment for child DBD, and in doing so, assess the anticipated financial costs and behavior improvements associated with its implementation and practice. First, we will review the extant literature and examine the implications, financial and otherwise, of untreated DBD. Next, we introduce PCIT and demonstrate the empirical support for the use of PCIT for children with DBD. Following such an introduction, we commence with an analysis of the costs and anticipated behavior changes associated with the use of PCIT on a per-child basis. Additionally, we discuss the startup costs necessary for implementing PCIT. Lastly, we conclude with a discussion of the implications of the results and suggest future directions for research in this area. We hope that this paper will encourage the use of PCIT in new settings, including both community and university clinics. Particularly when considering the exuberant costs of DBD, PCIT may be an attractive option to clinicians and policymakers if it is demonstrated to be a cost-effective treatment. The class of externalizing behaviors referred to as DBD is generally typified by aggressive, defiant, and impulsive behaviors which are commonly diagnosed as either Conduct Disorder (CD) or Oppositional Defiant Disorder (ODD). CD is characterized by aggression, theft, destruction of property, and defiance of societal norms. ODD is defined as a persistent pattern of behavior which includes arguing, disobedience of adult requests, and anger. All, by definition, lead to clinically significant impairment in the academic, interpersonal, and/or occupational domains (American Psychiatric Association, 2000). Additionally, these disorders are typically present early in life and can be recognized in children as as two years of age (Muntz, Hutchings, Edwards, Hounsome, & O'Celleachair, 2004). Among the numerous biological and situational correlates for the development of DBD, some of the strongest data indicate that family factors greatly contribute to child behavior. Indeed, among others, parental depression (Querido, Eyberg, & Boggs, 2001), reports of parental stress (Eyberg, Boggs, & Rodriguez, 1992), and parent-child interactions (Olson, Bates, & Bayles, 1990) have all been demonstrated to be associated with the display of child disruptive behavior. Indeed, research on this population indicates that parent-child interactions are one of the strongest determinants of the development of childhood behavior problems (Campbell, 1997; Patterson, 1982). Given the severity of these behaviors, there is a strong need for effective and early interventions. McNeil, Capage, Bahl, and Blanc (1999) reported that young children with severe behavior problems do not immediately 'outgrow' their disruptive behaviors without intervention (p. 451). Such a statement is not hyperbole as early-onset disruptive behavior is indicative of an especially poor prognosis (McMahon & Wells, 1998). …