This report presents an assessment of the Growth Capital Aggregation Pilot. It was commissioned by the Edna McConnell Clark Foundation, founder and lead investor of the grantmaking initiative. Starting in 2000, The Edna McConnell Clark Foundation (Clark) adopted an investment approach to grantmaking that focused on providing growth capital to youth-serving organizations with demonstrated commitments to evaluation and measurable outcomes. For grantees, the strategy meant larger, longer-term, unrestricted investments, complemented by extensive access to consulting and technical assistance to strengthen their organizations. This approach helped Clark grantees across the portfolio increase the numbers of youth they served (for example, by 18 percent between 2005 and 2006) and achieve annual revenue gains (averaging 19 percent over the four years prior to the founding of GCAP). At the same time, the Foundation concluded that more capital would be required if its grantees and other promising youth-serving organizations were to realize their ultimate scale and sustainability potential.