Association for Public Policy Analysis & Management

In 2010 Governor Schwarzenegger signed the Kindergarten Readiness Act into law in California. Prior to this law, children born on or before December 2 were eligible for Kindergarten. The law gradually moved the cutoff date to September 2 and established a Transitional Kindergarten (TK) year for students born between December 2 and September 2. The first cohort of children enrolled in TK in the 2012- 2013 school year.

TK is meant to provide a modified Kindergarten curriculum that is more age and developmentally appropriate for younger students (California Department of Education, 2013). Though the law mandated the establishment of these programs, each district has considerable leeway in the implementation of the law. Currently throughout the state about 120,000 students are experiencing TK a year (Quick, H. et al, 2014), but little is known about the program or its effects. A review of the first year of implementation found that school districts throughout the state were implementing the law in ways that provided substantially different experiences than Kindergarten (Quick, H. et al, 2014).

This study examines the effect of TK on student outcomes of the first two cohorts of students in a large urban school district in California. It leverages a Regression Discontinuity approach to causally identify the effects of TK on student academic outcomes. Two discontinuities are analyzed. The first compares the academic outcomes of students who were just old enough to qualify for TK to the academic outcomes of students who were slightly too young. These younger students consequently experienced all other pre-kindergarten options such as a district pre-kindergarten program, a private pre- kindergarten program, day care, or home care. The second discontinuity compares academic outcomes of students who were just young enough to be eligible for TK to those of students who were just old enough to attend a traditional kindergarten class.

Results provide insight as to whether this district’s attempt to align a curriculum with student development is truly beneficial for its students. These results are especially important as California considers continued funding of the law and can provide guidance for other states that may be considering adopting similar legislation.