This chapter presents what we know about the importance and impact of early childhood education, from research on the development of young children’s brains and from longterm research on the effects of early childhood programs. Abuse, poor care, and harsh settings inhibit the development of young children’s brains. Model early childhood programs for children from such environments contribute to their success in school and life, providing high return on investment. The United States has many early childhood programs and policies, including Head Start, the Child Care and Development Fund, preschool special education, state preschool programs, and child care programs in centers and in homes. Various studies show that typical and even special publicly funded early childhood programs have modest effects on children’s literacy and social skills and parents’ behavior. Certain model early childhood programs and model parent education programs contribute much to participants’ lives, but many of our publicly funded programs are not of this quality and effectiveness. We need to know what ingredients are necessary to cross the threshold of quality and effectiveness so that many programs can achieve the great contributions to children’s development of which they are capable.