Given the recognised importance of self-regulation (SR) and executive functioning (EF) in young children's academic and social-emotional wellbeing, their development should not be left to chance. This mixed methods study investigated whether the children taught by educators trained in the SOWATT program, a purposively designed professional learning program targeting self-regulation and executive functioning, would achieve better outcomes on a range of SR/EF measures than a control group who followed their usual program. Participants were 14 educators and 106 children, between the ages of 4 and 5 years, from four early childhood centres, run by the same not-for-profit organisation in Melbourne, Australia. Following a six-month intervention period, multiple regression analysis of pre and post task-based measures and a behaviour rating questionnaire, indicated that the children in the intervention group had made significantly greater gains than those in the control group. Qualitative data obtained from questionnaires and semi-structured interviews, confirmed the acceptability of the program by educators as easy to implement, and as a catalyst for change in their practice. Findings support previous research that building educator capacity through in-service professional learning is a viable, and potentially sustainable approach to improving young children's self-regulation and executive functioning abilities.