Four-year-old children in a school district near Denver were randomly assigned to either half-day (n=112) or full-day (n=114) preschool classrooms. To examine the impact on children's outcomes, Allison Atteberry and colleagues assessed children's receptive vocabulary skills using a standardized test in which children point to one of four pictures that best corresponds to a spoken word. The researchers also administered a developmental screening tool to assess children's developmental abilities in relation to school readiness. Both assessments were conducted within the first month of the first term, and again in the last month of the last term.