California is expanding transitional kindergarten (TK) to become a universal preschool program for all four-year-old children. Upwards of 300,000 children are expected to enroll in universal transitional kindergarten (UTK) by 2025, requiring thousands of additional lead teachers and classroom aides to meet lower student-to-teacher ratio requirements and new student demand. This report presents the first comprehensive data collected from California's transitional kindergarten teachers about their teaching experiences. In the fall of 2020, the Center for the Study of Child Care Employment (CSCCE) surveyed almost 300 TK teachers in classrooms throughout California as part of the California Early Care and Education Workforce Study. This report provides an exploratory picture of the composition of the TK workforce, the characteristics of the TK job, and the experience of teaching TK. Recommendations for policymakers conclude the study.