Montessori school...3 full days a week, starting tomorrow. We've been off for the summer. We had a traditional age-graded day care/preschool from 18 months until almost 4 years old, but once they started getting into more "school readiness" DS was so far beyond what they were doing it was not a good fit. We've been happy with the Montessori school, and he seems to be excited about going back tomorrow.