In 2021-2022, the Madison Education Partnership (MEP), in collaboration with the Madison Metropolitan School District (MMSD) Departments of Early Learning and Research & Innovation, conducted an evaluation of the program to understand how enrolling in full-day four-year-old kindergarten (4K) affects student learning relative to half-day 4K. We assessed differences in gains in achievement, as well as qualitative differences in instruction, time use, and culturally responsive practices across full- and half-day classrooms. (author abstract)