The current study examines the allocation of instructional time in half-day versus full-day pre-Kindergarten (pre-K) classrooms within a Colorado public school district that predominantly serves Hispanic and low-income students. Using 114 observations from 34 pre-K classes over two years, with up to 14 repeated observations per teacher, we analyze the distribution of time across various activities and content areas. We find substantial variation in time allocation between half- and full-day classes, especially regarding instructional and non-instructional activities, suggestive of potential differences in learning opportunities across the school year. Notably, full-day classes include a daily nap within their additional hours. Furthermore, we observe a considerable portion of classroom time dedicated to mixed-content activities, highlighting the multidimensional nature of time use in school-based pre-K. Our study's description of time allocation in this district also provides context for the previously published causal effects of the Full-Day Pre-K Study. Ultimately, the present study fills a gap in the body of research on time use in this early childhood education setting and informs stakeholders who are considering the expansion of pre-K programs to include a full-day option.