The Boston Foundation shifted its health grantmaking focus in 2009 to address the rising rates of preventable chronic illness and associated healthcare costs stemming from obesity. Recent studies show obesity rates among young children, especially low-income children and children of color, are alarmingly high. The document outlines a new 5-year initiative funded by The Boston Foundation to develop and test an intervention targeting the first 1000 days of life, from conception to age 2, to reduce obesity risk and disparities among vulnerable families through improved behaviors and outcomes for both mothers and children. The goal is to establish an effective model for necessary systemic changes to address early childhood obesity, especially in high-risk populations.