Since the mid-1990s, constituency building and advocacy for better public education have grown steadily in New York City. "Working Together to Achieve Greater Impact" explores how that growth was fueled by the Donors' Education Collaborative of New York, which pools its members' financial resources and expertise to advance shared grantmaking goals. The case study illustrates the importance--and challenges--of the sixth of Grantmakers for Education's eight Principles for Effective Education Grantmaking: "leverage," "influence" and "collaboration." [For the full report, "Working Together to Achieve Greater Impact: The Donors' Education Collaborative of New York City. Principles for Effective Education Grantmaking. Case Study Number 3," see ED537197.]