This article presents long-term effects of a preventive intervention for young children at high risk for antisocial behavior. Ninety-two children (M age ? 4 years) were randomly assigned to an 8-month family intervention or no-intervention control condition and assessed 4 times over a 24-month period. Intent-to-treat analyses revealed significant intervention effects on observed child physical aggression, and significant intervention effects found at the end of the program were maintained at follow-up for responsive parenting, harsh parenting and stimulation for learning. Parent ratings of child aggression did not show significant effects of intervention.
IYS has also been evaluated as a preventive intervention with low-income preschoolers and toddlers (Gross et al., 2003; Webster-Stratton, 1998; Webster-Stratton, Reid, & Hammond, 2001). As a preventive intervention, the program has been found to have short-term benefits on parenting practices, child social competence, and conduct problems in Head Start children (Webster-Stratton, 1998; Webster-Stratton et al., 2001). The program was found to be effective for a higher risk subgroup of the Head Start sample, defined as children of mothers with mental health problems and children with elevated behavior problems (Baydar, Reid, & Webster-Stratton, 2003; Reid, Webster-Stratton, & Baydar, 2004). However, long-term effects on parenting practices and child physical aggression are not known. The study presented here extends this work by testing the long-term effects of an adapted version of the IYS on parenting practices and physical aggression in children at especially high risk for antisocial behavior because of their family history of delinquency. Specifically, our study included children with delinquent siblings, a group that has proven to be at significant risk for antisocial behavior (Bank et al., 2004; Compton, Snyder, Schrepferman, Bank, & Shortt, 2003; Conger & Rueter, 1996; Patterson, 1984; Reid, Patterson, & Snyder, 2002; Reiss, Neiderhiser, Hetherington, & Plomin, 2000; Rodgers et al., 2001; Rowe, Almeida, & Jacobson, 1999; Rowe, Rodgers, & Meseck-Bushey, 1992; Slomkowski et al., 2001; Wasserman, Miller, Pinner, & Jaramillo, 1996).