<p>This study examined the feasibility and preliminary signals of change associated with PEACE, an intervention designed to reduce emotional distress and support emotional regulation in children with developmental disorders attending after-school care facilities in Japan. The program was delivered using narrated slides and worksheets, and staff members received training to support implementation. A total of 13 children were initially assigned to the intervention group, of whom 7 were included in the final analysis, and 32 children were included in the control group. The study employed a quasi-experimental design with pre-intervention, post-intervention, and three-month follow-up assessments. Outcome measures included caregiver and staff ratings of emotional problems, hyperactivity/inattention, and social skills. Caregiver ratings suggested a reduction in emotional problems, whereas no consistent changes were observed in staff ratings. Given the small and imbalanced sample, these findings should be interpreted as preliminary. Qualitative data indicated variability in children’s engagement and responses, suggesting that the program’s acceptability and usefulness may depend on individual characteristics such as developmental level and cognitive functioning. Overall, the findings support the feasibility of implementing the program in after-school care settings while highlighting the importance of adapting content and delivery to individual needs. Further research with larger samples and more detailed measures is needed to clarify the mechanisms underlying observed changes and to evaluate effectiveness more rigorously.</p>