Between 1995 and 2004, Early Head Start (EHS) grew from 68 to more than 700 programs nationwide, serving more than 62,000 children and securing the program's reputation as a beacon of hope for the nation's low-income families with infants and toddlers. According to a comprehensive 5-year national evaluation of EHS, children who participated in the program scored higher on standardized measures of cognitive and language development, exhibited greater engagement with their parents during play, and were less likely to engage in aggressive behavior than children who did not participate. Additionally, program parents were more emotionally supportive and less detached, were more likely to read to their child every day, reported spanking their child less frequently, and were more likely to seek out education and job-training activities than parents who did not participate in the program. The articles in this volume describe the variety of EHS services and analyze the successes and challenges revealed by the data from the 5-year national evaluation. Topics include: child care for low-income families, services for pregnant women, work with fathers, early learning, teen parents, infant mental health, early intervention, and state partnerships. The volume can be used to introduce early childhood professionals, community leaders, parents, policymakers, and early childhood students to EHS.