AIR Study Finds California’s Transitional Kindergarten Gives English Learner Students Advantage for Kindergarten

Washington, D.C. – English learner (EL) students who attend California’s transitional kindergarten program enter kindergarten with stronger English language, mathematics and literacy skills than English learners who did not attend transitional kindergarten, according to a new study released today by the American Institutes for Research (AIR). The study is based on AIR’s multi-year study of transitional kindergarten in California, a state where one-third of kindergartners are classified as English learners.

Transitional kindergarten in California was established by the state’s Kindergarten Readiness Act, passed in 2010. Historically, the state required children to be 5 years old by December 2 to enroll in kindergarten. When the new law moved the cutoff to September 1, transitional kindergarten was created for children who turned 5 between September 1 and December 2. 

“The effects of transitional kindergarten on EL students’ language, literacy and mathematics skills are quite significant as these young children prepare for success in kindergarten and elementary school,” said Karen Manship, AIR principal researcher and study director. “The additional year of school appears to provide a distinct advantage for English learners over their peers who were not eligible for transitional kindergarten.”

Using the age cutoff to compare children who were eligible for transitional kindergarten to their non-eligible peers, the report estimates the impact of transitional kindergarten on school readiness skills of more than 2,600 English learners across 20 districts. The study also measures the English language development scores of nearly 55,000 English learners statewide tested at kindergarten entry. This study design enables researchers to attribute differences in outcomes between transitional kindergarten students and non-transitional kindergarten students, though the generalizability of the results to students outside the narrow age range around the cutoff date may be limited.

Notable findings include:

  • EL students from all language groups who attended transitional kindergarten experienced a substantial boost in their English language development, including speaking skills, listening skills, and overall language proficiency. This puts transitional kindergarten students ahead of their peers by 60 points or a full performance level on the California English Language Development Test.
  • Transitional kindergarten improved mathematics skills for EL students, giving them a nearly six-month learning advantage over EL students who did not attend transitional kindergarten.
  • Transitional kindergarten improved EL students’ literacy skills, putting them ahead of their peers who did not attend transitional kindergarten by more than seven months of learning at kindergarten entry.
  • No impact was observed on EL students’ social skills or executive function at kindergarten entry. EL students entering kindergarten with and without transitional kindergarten had similar skills in these areas.

Researchers in the San Mateo, California office of AIR have been studying the state’s transitional kindergarten program since 2011, with support from the Heising-Simons Foundation, the David and Lucile Packard Foundation and First 5 California. The report, Transitional Kindergarten in California: The Impact of Transitional Kindergarten on English Learner Students, is the latest from the multiyear study. Past reports, including one that examines transitional kindergarten’s impact on all students and the characteristics of transitional kindergarten classrooms, can be found on the study’s website.

About AIR
Established in 1946, with headquarters in Washington, D.C., the American Institutes for Research (AIR) is a nonpartisan, not-for-profit organization that conducts behavioral and social science research and delivers technical assistance both domestically and internationally in the areas of health, education, and workforce productivity. For more information, visit


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