This brief describes the impact of the Montgomery County (Maryland) Public Schools (MCPS) 2007-2008 full-day Head Start prekindergarten (pre-K) class model on student academic performance, cognitive skills, and learning behaviors by the end of Grade 2. This is the fourth impact study of the MCPS full-day Head Start pre-K class model. The following are appended: (1) Original pre-K Cohort in 2007-2008; (2) Construction of Overall Learning Skill Score Based on 2010-2011 Traditional Report Cards; (3) Covariate-Adjusted Model and Findings; (4) Comparing Full-day Head Start pre-K and MCPS Partial-day pre-K Classes With Propensity Score Matching; and (5) Comparing Full-day Head Start pre-K Classes and Students Who Had No MCPS pre-K Experience After Propensity Score Matching.