UC Berkeley Study: California Pre-K and K-5 Spending Boost Achievement

Universal prekindergarten rollouts across California yielded reading levels roughly a full grade ahead and math performance about two-thirds of a grade higher among third- and fourth-grade student groups, based on a 2026 University of California, Berkeley analysis by R. C. Johnson and A. Land. State investments in early education have grown from seven states in 1980 to 44 states and the District of Columbia by 2021.

Early Childhood Programs Boost Reading and Math Gains

• Children affected by the Kindergarten Readiness Act who accessed transitional kindergarten at age four and attended the California State Preschool Program at age three showed reading gains of nearly a full grade level and math gains of about two-thirds of a grade level by the third and fourth grades.
• Low-income children with English-speaking parents gained about seven months of additional learning in third-grade math and reading from transitional kindergarten attendance, with even larger effects when preceded by the California State Preschool Program.
• State funding commitments reached roughly $4.1 billion for transitional kindergarten and $2.8 billion for the California State Preschool Program in the 2025–26 budget as universal preschool phased in for all four-year-olds.

How California Shaped Three Decades of Early Education Reform

Early childhood education has emerged as standard practice for the majority of young American children, yet prohibitive expenses keep it out of reach for numerous households. Ensuring that all children can access early education advantages irrespective of household wealth is the central goal of public preschool initiatives. State investments have grown rapidly, from seven states funding preschool in 1980 to 44 states and the District of Columbia by 2021. Data indicates that academic improvements from preschool are typically most pronounced among multilingual learners and children from economically disadvantaged households, who frequently enter kindergarten possessing lower baseline academic measurements.

At the same time, the field has long wrestled with two puzzles. First, the initial gains from preschool frequently appear to fade as children move through elementary school. Moreover, the long-term impact of preschool may heavily hinge upon surrounding educational factors: namely, the foundational learning experiences children undergo at age three coupled with the academic rigor of their subsequent primary schools. Although researchers have theorized that early educational investments and subsequent schooling work synergistically, solid empirical backing has historically been limited.

California offers a rare opportunity to study these questions at scale. Starting in 2009, the state implemented three separate policy changes affecting successive generations of children at distinct developmental milestones: unifying state preschool funds under the California State Preschool Program, establishing transitional kindergarten via the Kindergarten Readiness Act, and restructuring district allocations through the Local Control Funding Formula.

What Did the Study Discover About Student Achievement Gains?

As documented by University of California, Berkeley investigators, student groups impacted by the Kindergarten Readiness Act—who utilized transitional kindergarten at age four alongside significantly elevated participation rates in the California State Preschool Program at age three compared to preceding generations—demonstrated third- and fourth-grade reading outcomes nearly a full grade ahead and math results roughly two-thirds of a grade higher than benchmark groups from earlier years. For children from low-income backgrounds with English-speaking parents, transitional kindergarten attendance led to about seven months of additional learning in third-grade math and reading. Effects were much smaller for children from more advantaged backgrounds.

Among low-income children, transitional kindergarten effects were larger for those who first attended the California State Preschool Program. Low-income multilingual learners had nearly half a year of additional learning gains in fourth-grade math when their transitional kindergarten attendance was preceded by the preschool program.

Student Subgroup	Intervention Sequence	Estimated Learning Gain
General Affected Cohorts	Transitional Kindergarten + California State Preschool Program	Nearly 1 grade level (reading); ~2/3 grade level (math)
Low-Income Children (English-speaking parents)	Transitional Kindergarten Attendance	~7 months additional learning (math and reading)
Low-Income Multilingual Learners	California State Preschool Program followed by Transitional Kindergarten	Nearly half a year additional learning (4th grade math)

Why Did the Kindergarten Readiness Act Alter Early Learning Timelines?

Prior to the passage of the Kindergarten Readiness Act, California enforced a December 2 kindergarten cutoff date that ranked among the latest nationwide, meaning children turning five during the autumn months frequently entered kindergarten as four-year-olds. Wealthier households were financially equipped to postpone kindergarten entry—redshirting their children to secure an extra year of preschool—whereas poorer families generally lacked this option, thereby bestowing an uneven developmental advantage upon economically privileged youth.

The Kindergarten Readiness Act of 2010 addressed this inequity by moving the kindergarten eligibility cutoff and creating transitional kindergarten as the first year of a two-year kindergarten program for children with fall birthdays, spanning September 2 to December 2. Transitional kindergarten is California’s first universal prekindergarten program. Eligibility is based solely on birthdate, and all districts are required to offer it.

Although the Kindergarten Readiness Act did not directly change the California State Preschool Program, it reshaped the timing and sequence of early education for children with fall birthdays. The share of children enrolling in the California State Preschool Program at age three rose from 8% before the Kindergarten Readiness Act to about 20% afterward.

How Do Funding Interventions Reinforce Preschool Outcomes?

In the decade before the Local Control Funding Formula, California consistently ranked among the lowest 15 states in per-pupil spending adjusted for cost of living. Adopted in 2013, the Local Control Funding Formula boosted per-pupil allocations and funneled financial backing toward school districts based on their share of English language learners, foster youth, and low-income students. Total monetary support allocated to public K–12 institutions within the 2022–23 state financial plan stood at approximately three times the funding level recorded in 2011.

A $1,000 increase in per-pupil spending for the California State Preschool Program led to almost a quarter of a year of additional learning in math and reading three and four years after kindergarten, independent of transitional kindergarten and school spending. Transitional kindergarten attendance and Local Control Funding Formula-induced school spending were mutually reinforcing, meaning transitional kindergarten effects grew with elementary school funding and persisted longer in better-resourced schools.