When every child has the opportunity to meet his or her full potential, families, communities, and the nation's economic future strengthens. Remarkably, one in four American children come from low-income families and enter kindergarten not ready to learn and, as a result, fall behind from the very start. The nation pays a heavy price through larger taxpayer burdens in remedial and special education, more costly health interventions, and increased criminal justice expenditures. Research shows that for a fraction of those costs, preventive investments in high-quality early childhood programs can avoid the high price of remediation and bring enormous benefits to the economy. Further, early intervention strengthens families and accelerates a child's ability to learn, thus increasing the effectiveness of K-12 education. America vastly underinvests in early childhood programs that work, especially in the critical period from pregnancy to age three. This guide offers numerous specific, evidence-based public investment opportunities private donors and government can pursue immediately to make an impact. Philanthropy, business, and government must work together to expand early childhood opportunities so that all children arrive at school ready to learn and with an equal chance to achieve success throughout their lives. The following are appended: (1) List of Interviewees; (2) Sources; and (3) ECLS-B Technical Appendix.