This study examines the effectiveness of a School-Based Mindfulness Program (SBMP) designed to support attention regulation, emotion regulation, self-awareness, and self-compassion in preschool children aged 48-72 months. The intervention was implemented in preschool classrooms over eight weeks and consisted of 24 structured sessions. A quasi-experimental design with two experimental groups (researcher-led and teacher-led implementation) and one control group was used. School readiness outcomes were assessed using the School Readiness Assessment Tool (SRAT).