Kindergarten transition programs support successful school transitions for families and may reduce disparities in academic readiness upon school entry. Yet, access and participation in high-quality summer transition programs are lower among children from disadvantaged backgrounds. This study examined the impact of a summer kindergarten transition program on children's readiness in language and literacy, mathematical thinking, and social foundations and the strength of their home-school relationships. Assessment scores of 416 kindergartners within 30 classrooms in 28 elementary schools in one southeastern state were analyzed. Children who participated demonstrated significantly more readiness in their language and literacy, mathematical thinking, and social foundation skills compared with children who were eligible but did not participate in the program. Further, children who participated in the program had significantly stronger home-school relationships compared to children who were eligible but did not participate and those who were not eligible to participate in the program. The findings provide preliminary evidence that summer transition programs are an equitable strategy to reduce achievement gaps upon kindergarten entry. School administrators should consider implementing summer transition programs to support academic readiness and develop strong home-school relationships in communities with a high population of children who are at risk for later school difficulties.