This study examines the effects of Head Start enrollment duration on developmental outcomes for children who have had adverse childhood experiences (ACEs). This study utilizes randomized control Head Start Impact Study data, to address three primary questions: 1) Do children’s ACE scores have any impact on cognitive, socio-emotional and health care service outcomes? 2) Do the number of years enrolled in Head Start have any impact on children’s outcomes? 3) Does the impact of enrollment duration in Head Start on children’s outcomes differ depending on number of ACEs? (author abstract)