The Countdown to Kindergarten (CTK) program was developed to increase family awareness of kindergarten expectations, create a positive relationship with families, and support smooth school transition and kindergarten readiness for children who were from diverse backgrounds and/or had adverse experiences. We used a mixed methods design to study the impact of CTK on 320 children in 16 randomly selected kindergarten classrooms. We found that children who participated in CTK demonstrated more academic readiness, more family engagement, and substantially stronger home school relations than those who were eligible but did not participate in CTK. Children who participated in CTK demonstrated confidence and strong communication and leadership skills. The findings could inform the development of kindergarten transition programs and policy making.