A two-part study explored the maintenance effect of Behavioral Parent Training (BPT) featuring multi-component treatments by examining one year follow-up data from a larger study. Participants were ten parents of children (ages 3-5) with developmental disabilities and severe problem behaviors. Parents were also identified as having high levels of pessimism. BPT featuring multi-component treatments was provided in two conditions: Positive Behavior Support (PBS) and Positive Family Intervention (PFI). PBS included a standardized protocol to teach parents how to conduct a functional assessment, develop and implement a multi-component treatment, which includes the following strategies: prevention, teaching replacement skills, and managing consequences. PFI embedded optimism training in the same protocol used in PBS. Optimism training included presenting parents with their negative self-talk and having them practice using more positive self-talk throughout all sessions. In the first study, improvements in child behavior were observed after treatment, which maintained one year later for both conditions. The second study further revealed that participants in the PBS condition frequently used passive strategies vs. participants in the PFI condition who frequently used proactive strategies during post and one year follow-up. The current study did not reveal a specific treatment component to be responsible for behavior change and maintenance, but provided some insight as to the type of prevention strategies pessimistic parents are likely to use depending on whether or not they received optimism training. Suggestions for future research in assessing the remaining treatment components are discussed.