From 2009-10 to 2018-19, three major public investments in educational opportunity reshaped California's preschool and elementary school landscape. First, in 2009, the state created the California State Preschool Program (CSPP) to consolidate fragmented funding streams into a single contract for publicly funded preschool serving three- and four-year-olds from lower- and middle-income families. Second, in 2012, the state began implementing the Kindergarten Readiness Act of 2010 (KRA), which (a) instituted a delay in the kindergarten eligibility start age for children turning age 5 late in the year (students who would otherwise be “young-for-grade”) and (b) introduced Transitional Kindergarten (TK) for those children in the year before kindergarten. The policy was a direct response to the advantage of entering kindergarten later, an advantage that was out of reach for many families who could not afford to delay kindergarten entry due to the high costs of child care. Third, in 2013, the state began implementing the Local Control Funding Formula (LCFF), which overhauled California's K-12 finance system, increasing levels of funding and directing per-pupil funding to districts in proportion to their enrollment of English learners, low-income students, and foster youth. Each reform directed resources disproportionately to disadvantaged children and districts, reflecting a sustained state commitment to narrowing disparities in educational opportunity. Together, these three investments reached successive cohorts of children with varying degrees of intensity during sequential developmental stages of childhood.
We leverage the staggered implementation of these reforms to estimate the independent causal effects of CSPP per-pupil spending and TK attendance on math and reading achievement in grades 3 and 4, and to identify potential synergistic effects between TK attendance and LCFF-induced increases in elementary school spending. We use population student-level administrative longitudinal data for the full universe of California public school students, focusing on the period from 2009 through 2019. To facilitate causal inference, we exploit three sources of quasi-experimental variation: CSPP contractor-level funding shocks, birthdate cutoffs for TK eligibility, and the staggered rollout of LCFF-induced changes in per-pupil elementary school funding. Each source supports a distinct identification strategy, and we integrate these strategies within a unified framework to estimate each investment's independent causal effects on student achievement and to identify potential interactions across them. We supplement these findings with event study analysis of the KRA’s overall effect on math and reading achievement.
California's investments in CSPP, TK, and elementary school spending delivered substantial, equity-enhancing gains in student achievement, and their effects reinforce one another across the preschool and early elementary grades. The results suggest that sequenced public investments in educational opportunity can produce developmental multiplier effects that exceed the sum of their independent effects.
Summary of Key Findings
- $1,000 increase in CSPP per-pupil spending led to almost ¼ of a year greater learning gains in math and reading achievement three and four years after kindergarten.
- Among students whose parents are low-income and speak English, TK attendance led to 6 months more learning gains in 3rd grade reading and math achievement on average, relative to the typical student from the same school in the same kindergarten cohort who did not attend TK.
- Average effects on students with parents who do not speak English were relatively modest. TK attendance led to about 1.8 months of learning gains in math achievement and 2.4 months in reading achievement.
- TK impacts on both math and reading achievement among socioeconomically disadvantaged students were significantly larger among those who first attended CSPP at age 3. TK impacts on reading and math scores were roughly 0.2-grade-levels higher for these early CSPP-goers.
- TK led to roughly half a year of learning gains in math and reading for students with non-English-speaking parents, when preceded by CSPP attendance.
- Achievement gains were consistently and substantially larger in schools with higher levels of per-child funding.
- TK-induced gains in 3rd-grade math and reading achievement persisted into fourth grade
- Gains in math were particularly persistent.
- Persistence appears stronger where per-child funding was higher.
- Gains induced by TK participation and increases in per-child funding were mutually reinforcing: TK attendance and LCFF-induced spending increases exhibit positive, synergistic impacts.
- Significantly smaller TK effects for non-poor children on average (likely due to greater access to high quality private preK in counterfactual care setting).
- Effects of TK attendance were found to be smaller for children whose parents are low-income and who do not speak English.
