The purpose of this study was to identify the predictors of change in parental stress (including parent and child factors), depression, and interaction style in parents of toddlers with Autism Spectrum Disorders (ASD), exposed to two types of early intervention (EI) programs, PLAY and Community Standard (CS). This study utilized secondary data of 128 parents of children with ASD from a controlled, randomized, experimental study conducted by Dr. Richard Solomon and colleagues at Michigan State University. Predictors of parent outcomes were identified, controlling for the confounding effect of type of treatment on the outcomes; whether these predictors differed based on treatment was also investigated. The study was guided by six research questions that utilized multivariate statistical approaches, including multiple regression analysis, multivariate analysis of covariance (MANCOVA), and multivariate analysis of variance (MANOVA). Changes in parent outcomes were calculated using gain scores or the difference between the posttest score and the pretest score. Significant predictors of change in parent stress included child age (R[superscript 2] = 0.048, p = 0.036) and marital status (R[superscript 2] = 0.094, p = 0.034), while the predictors of change in child stress were initial depression (R[superscript 2] = 0.095, p = 0.005) and family size (R[superscript 2] = 0.134, p = 0.046). The interaction between child age and treatment was a significant predictor of change in parent stress, indicating that the older the child the greater the reduction in parent stress, only for parents participating in the PLAY intervention. Significant predictors of change in depression were parent stress (R[superscript 2] = 0.155, p < 0.001), other children with ASD (R[superscript 2] = 0.222, p = 0.005), marital status (R[superscript 2] = 0.266, p = 0.022), and family size (R[superscript 2] = 0.294, p = 0.05), and there was a significant interaction between parent stress and treatment. Significant differences among household income categories were found in parent-child interaction gain scores after controlling for treatment, Wilks' Lambda = 0.834, F (8,208) = 2.469, p = 0.014. There was not a significant interaction between treatment and income, suggesting that those who participated in PLAY significantly improved their interaction styles, regardless of income. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]