Universal parenting programs, which are preventative social services seeking to strengthen parent child relationships, are not as common as those targeting specific physical or behavioral conditions in children. They have been evaluated less frequently, and yet their focus on prevention rather than treatment can lead to long term social and economic gains. Parents Building Solutions (PBS) is a universal, group-work parenting program where a skilled facilitator uses a co-design methodology to develop the program's agenda and content with parents. A pilot, quasi experiemental pre-test post-test trial was conducted to determine the program's efficacy in fostering increases in parenting quality, confidence, self-efficacy, and parental understanding of child development, as well as improving the ability of parents to respond effectively to children's behavior. Attrition was also measured. Data was collected at three time points from 58 parents (baseline) in three regions in Melbourne, Australia. Statistically significant differences were seen for all measures, with large effect sizes. Attrition was low with 90% of participants completing the program. Using a co-design methodology as a way to engage and retain parents may be a critical factor in the success of PBS, however further research is needed to firmly establish efficacy.