This study examined the effectiveness of a parent training program, Parenting Support Program (PSP), on parenting styles, parenting competence and parenting stress. The quantitative part of the study utilized a randomized, controlled trial to test the efficacy of Parenting Support Program (PSP). In the qualitative part of the study, parents' opinions about the PSP and their behaviors were evaluated as to whether they supported the experimental findings. Parents of children (n = 18 mothers and 11 fathers) were randomly assigned to an experimental group (EG) and a wait-list group (WL). The experiment group attended a total of individually delivered 12 sessions of PSP. Data were gathered via parent-report measures, observation, and semi-structured interviews. Provided that it is more limited in fathers, PSP was effective in increasing authoritative parenting styles and in decreasing authoritarian and permissive parenting styles. Moreover, PSP was found to effective in in- creasing parenting competence, but not in decreasing parenting stress. A relatively high percentage of parents in the EG re- ported a clinically significant change in their attitudes and behaviors, as shown by the Reliable Change Index. Consequently, the current study demonstrates that PSP can be used as an intervention program to develop positive parenting behaviors.