Tiered evidence initiatives are an important federal strategy to incentivize and accelerate the use of rigorous evidence in planning, implementing, and assessing social service investments. The Social Innovation Fund (SIF), a program of the Corporation for National and Community Service, adopted a public-private partnership approach to tiered evidence. What was learned from implementing this ambitious program? How can large funding initiatives promote evaluation capacity in smaller organizations and evidence building in a sector broadly, increasing knowledge about how to address important social problems? And what can evaluators and evaluation technical assistance providers not working within a tiered evidence framework learn from the SIF? We provide an overview of the SIF model and describe how the fund operationalized "evidence building." Materials developed to support SIF grantees represent practical, best practice strategies for successfully completing rigorous, relevant evaluations. Key lessons from overseeing over 130 evaluations--and their utility for other local evaluators--are discussed.