In July 2011, NewSchools launched a four-year, $12 million fund that focused on adding new, high-quality charter school seats in Boston. The Boston Fund took important steps toward ensuring that all children in Boston have the opportunity to attend a quality school. By helping establish high-performing school ventures and by developing a supportive ecosystem, the Boston Fund was able to double the size of the highest-performing charter sector in the country. This report looks back on the successes, challenges, and lessons learned over the four years of the fund.