Physical punishment of children is linked to negative developmental outcomes. The widely used Positive Parenting Program (Triple P) promotes alternative responses to physical punishment. Data on the effectiveness of the Triple P Seminar Series is limited. In this study, Canadian parents’ reports of physical punishment, non-physical punishment, and non-punitive responses were compared before and after they attended the Triple P Seminar Series. Twenty-seven parents of children aged 2 to 6 years attended the Seminar Series and completed pre- and post-intervention questionnaires measuring the number of times they used various physical punishments, non-physical punishments, and non-punitive responses in the past month. Hypotheses were tested using univariate descriptive analyses, paired samples t tests, and Wilcoxon Signed Rank Tests. Parents’ reports of physical punishment decreased on only one of the four physical punishment items (shaking/grabbing) from pre- to post-intervention. Over the course of the Seminar Series, parents became more likely to emphasise rules and to punish their children by taking things away from them. The findings suggest that the Seminar Series has limited effectiveness in reducing physical punishments or increasing non-punitive responses. Further research on this question is needed.