This study investigates preschool teachers' experiences and perceptions of a professional development (PD) program on children's self-regulation. This PD opportunity was planned around two aims: to increase preschool teachers' awareness of children's self-regulation skills and to support participants' understanding and skills to implement the Red Light, Purple Light (RLPL) Self-Regulation Intervention Program in their classrooms. The phenomenological research design is used to examine participant teachers' experiences in the PD program. The participants consist of 23 volunteer public preschool teachers. Data sources were semi-structured interviews and reflective writings. Based on the results of the content analysis, the participating teachers thought that the PD program positively affected their personal and professional development. Participating in the PD program broadened their understanding of the conceptual basis of self-regulation in children. In addition, participants expressed their perceptions about embedding ways of fostering self-regulation in the National Preschool Education Program practices and the structural features of the RLPL Self-Regulation Intervention Program.