In a recent study of Head Start's impact on early childhood education, a meta-analysis reviewed 28 studies from 1965 to 2007. Head Start yielded a 0.27 effect size, indicating modest improvement in children's short-term cognitive outcomes, aligning with general early childhood education programs. Yet, its effects were smaller compared to more intensive programs like Perry Preschool, but within the range of wider ECE averages. Research design significantly influenced these outcomes, particularly the nature of the control group. Studies with an "active" control group, exposed to other forms of ECE, showed smaller effects than those with a "passive" group, receiving no alternative ECE. As ECE attendance rises, communities with multiple ECE options could produce smaller Head Start effects. This does not question Head Start's efficacy but highlights other effective ECE alternatives, skewing comparative evaluations. Skills closely tied to ECE curricula, like early reading and math, responded better to Head Start than broader cognitive skills, suggesting tempered expectations for effects on measures like vocabulary or IQ. Finally, the study emphasizes considering measurement quality when interpreting program evaluation outcomes.