The TK Question Our Field Is Exploring

An article by LAist recently pointed out that TK has continued to grow, and could benefit from formal evaluation. Please click here to read the article. If you're an early childhood provider in California, you've likely felt the shift that Transitional Kindergarten (TK) has brought to our system. Maybe you've seen enrollment change as four-year-olds transition into public school programs. Maybe families are asking questions about their options. Maybe you're curious about how TK experiences compare to the early learning environments you've spent years building. Across the field, many of us are asking a similar question: How is TK working for children and what can we learn from it? Right now, the honest answer is that we don't yet have a clear, statewide picture, and that presents an important opportunity.

When California launched Universal Transitional Kindergarten in 2021, it represented one of the most ambitious early learning expansions in the country. The vision was bold: expand access to early learning, help children enter kindergarten ready to thrive, and support families across the state. By fall 2025, more than 175,000 four-year-olds were enrolled in TK programs. Districts expanded classrooms, hired teachers, and made major investments to serve younger learners. It was a remarkable commitment to early childhood, and as with any major public investment, the next step is making sure we learn from it.

Early childhood educators understand something fundamental; that quality matters just as much as access. The environments children experience at age four shape their social development, their curiosity, their relationships with learning, and their readiness for school. That’s why many researchers believe this is an ideal moment to study TK closely. Providers know the importance of evaluating TK implementation to understand whether classrooms are providing developmentally appropriate learning experiences while also ensuring TK both supports families and delivers meaningful early learning experiences for children. Considering both of these ideas matter deeply, but to answer those questions well, the field needs good data.

One of the most interesting features of California’s TK system is that it allows districts flexibility in how programs operate. However, that flexibility has also led to a wide range of classroom experiences across the state. Some programs are deeply play-based and rooted in early childhood best practices. Others are still adapting elementary school environments to meet the needs of four-year-olds. Many districts are actively learning, adjusting, and improving their approaches as they expand. Without statewide evaluation, however, it becomes harder to identify which approaches are most effective, what supports teachers need, how children are experiencing these classrooms, and how TK and community-based preschool programs can best complement one another. These are exactly the kinds of insights that thoughtful research can provide.

California now has an opportunity to build a cache of evidenced based knowledge from the start. With TK expanding rapidly, researchers, educators, and policymakers all have a shared interest in understanding what works best for children. Some earlier research, including studies of California’s original, smaller TK program, offers helpful insights. However, the article points out that many researchers note that today’s universal program is significantly different in scale and design, making new research especially valuable. As the program continues to grow, the need for updated data becomes even more important. For California’s early childhood community, this moment presents a unique opportunity.

ECE providers bring decades of expertise in developmentally appropriate practice, play-based learning, family engagement, and whole-child development. Those lessons could be incredibly valuable as TK evolves. Thoughtful evaluation might help identify best practices for four-year-old classrooms, support TK teachers as they transition into early childhood approaches, strengthen alignment between TK and community-based preschool programs, and ensure that investments are truly supporting children's development. Evaluation could be about learning and strengthening the system together. California has made a historic commitment to four-year-olds and their families. That commitment deserves the same level of attention to quality, learning, and improvement that the early childhood field has long embraced. By investing in evaluation and shared learning, the state can ensure that TK continues to grow in ways that benefit children, families, and educators alike, and the early childhood community has an essential role to play in that process, because when it comes to supporting young learners, the best systems are the ones that keep learning themselves.