Across the country many schools and communities are trying to create and support efforts to institutionalize partnerships for learning, including those that rethink the use of time across the school day and year, and across the developmental continuum. Referred to by different terms--integrated, expanded, or complementary learning--the concept has one critical element in common: partners are able to create a web of learning and developmental supports for children and youth in which the linkages add up to more than the sum of their parts. The past 10 years have witnessed tremendous growth in programs and initiatives aimed specifically at developing and sustaining intentional partnerships between out-of-school time programs (OST) and schools in order to support--but not replicate--in-school learning and healthy development. This report is aimed to help OST program leaders, decision-makers, and funders to understand and implement effective OST-school partnerships for learning. Specifically, it: (1) describes the benefits of OST-school partnerships for children, schools, and OST programs; (2) presents five research-derived principles of promising OST-school partnerships, offering specific strategies and examples for each; (3) profiles three "on-the-ground" partnership efforts based on the in-depth interviews conducted at the three selected sites; and (4) discusses conditions for optimal success in developing sustainable OST-school partnerships. Appended is: Our Review Approach. (Contains 16 footnotes.) [This report was compiled by the Harvard Family Research Project Evaluation Team--Erin Harris, Sarah Deschenes, Helen Westmoreland, Suzanne Bouffard, and Julia Coffman--under the leadership and guidance of Priscilla Little, Associate Director of Harvard Family Research Project.]