Early educational interventions, such as Head Start, have been widely recognized as an effective way to mitigate the negative effects of poverty on early learning and development (Camilli, Vargas, Ryan, & Barnett, 2010). In the past decade, there has been a strong expansion of early childhood programming, including Head Start and state-funded prekindergarten programs. However, the cost of the programs calls into question the extent to which this expansion can be maintained. A tension exists between serving as many children as possible and providing the most impact with limited economic resources (e.g., Barnett & Hustedt, 2011; Steuerle, Reynolds, & Carasso, 2007), making the study of program design such as length and intensity of programming critical to efforts to serve low-income or at-risk children in the most efficient fashion. This paper reviews two frequently cited studies that looked at Head Start programs, the nation's largest early educational intervention, and examined the impact of one program factor, intervention dosage, on children's school readiness outcomes. In the two studies, program dosage was defined as the amount of services children received, and was measured as the duration of program enrollment (i.e., one year versus two years) and the intensity of the program (i.e., half day versus full day).