Social impairments characteristic of Autism Spectrum Disorder (ASD) are evident in early childhood and often worsen as an individual matures (Rao, Beidel, and Murray, 2008). Despite the emphasis on early intervention and caregiver training, few evidence-based interventions explicitly address the development of social skills in preschool-aged children with ASD (DeRosier, Swick, Davis, McMillen, and Matthews, 2011; Reichow and Volkmar, 2010) and none appear to actively integrate caregivers into treatment (Reichow, Steiner, and Volkmar, 2012). Research indicates that generalization beyond a social skills group setting might occur by including caregivers (DeRosier et al., 2011). The PEERS® program is an evidence-based caregiver-assisted social skills program for adolescents and young adults (Laugeson and Frankel, 2010) that has recently been extended for preschoolers with ASD. An initial randomized controlled trial (RCT) indicated benefits from the PEERS® for Preschoolers (P4P) program, but did not examine caregiver or family outcomes. Researchers also suggest a bidirectional effect in which the family system is impacted by the child with ASD and in turn, the child with ASD is also affected by the family (Karst and Van Hecke, 2012). This study examined the P4P curriculum with 15 children with ASD and their caregivers and examined feasibility of the intervention as well as child social skills, caregiver competency, confidence, and parenting skills in working with their child, and family functioning in the context of the P4P intervention. Results suggest the feasibility of proof concept of applying the P4P curriculum to young children with ASD and their caregivers. Specifically, this 16-session intervention appears to improve social skills scores in children with ASD, which is maintained 4-6 weeks after treatment, increased scores were noted in caregiver confidence interacting with their children, as well as improved scores in their affect/animation and achievement orientation in interaction styles with their child, and noted improvements in their parenting styles overall score. Therefore, this intervention may have an impact both the child and caregiver in positive ways and these positive results are largely maintained at a follow-up after intervention completion. Future research will need to focus more on the entire family unit, as no changes were noted in the present study, and should examine the specific mechanisms that lead to these positive results regarding child social skills and caregiver interaction styles and confidence. Additionally, more work that adds to making P4P an evidence-based treatment must be at the forefront of future work. / Doctor of Philosophy / Social difficulties (e.g., initiating and/or maintaining social interactions, using and/or interpreting verbal and nonverbal social communication, such as eye contact or gestures, understanding others' thoughts and emotions) characteristic of Autism Spectrum Disorder (ASD) are evident in early childhood and often worsen as an individual matures (Baron-Cohen and Wheelwright, 2004; Frith, 2004; Rao, Beidel, and Murray, 2008). Despite the emphasis on early intervention or treatment for individuals with ASD and caregiver (e.g., parent, grandparent, etc.) training, few evidence-based interventions exist that purposefully address the development of social skills in preschool-aged children (DeRosier, Swick, Davis, McMillen, and Matthews, 2011; Reichow and Volkmar, 2010) and none appear to actively involve caregivers in treatment (Reichow, Steiner, and Volkmar, 2012). Research indicates that generalization beyond a social skills group setting might occur by including caregivers (DeRosier et al., 2011). The PEERS® program is an evidence-based caregiver-assisted social skills program for adolescents and young adults (Laugeson and Frankel, 2010) that has recently been extended for preschoolers with ASD. An initial randomized controlled trial (RCT) indicated benefits from the PEERS® for Preschoolers (P4P) program, but did not examine caregiver or family outcomes. Researchers also suggest that there is often an effect on the entire family unit of a child with ASD, which in turn has an impact on the child with ASD (Karst and Van Hecke, 2012). This study examined the P4P curriculum with 15 children with ASD and their caregivers, and examined feasibility of the intervention as well as child social skills, caregiver competency, confidence, and parenting skills in interacting with their child, and family functioning in the context of the P4P intervention. Results suggest that this 16-session intervention appears to improve social skills scores in children with ASD, and these improved scores are largely maintained 4-6 weeks after treatment. Increased scores were also noted in caregiver confidence in interacting with their children as well as in their affect/animation and achievement orientation in interaction styles, and may also improve their parenting style scores overall. Therefore, this intervention may have an impact on both the child and caregiver in positive ways. Future research should address the entire family unit, as no changes were noted in the present study, and should also examine the specific factors that lead to these positive results, as further research adds to P4P becoming an evidence-based treatment.