This report draws on P/PV's seven years of experience working with Pennsylvania's Nurse-Family Partnership initiative. Those years have made clear that the replication of evidence-based programs can be an enormous challenge, even for highly defined and effective programs like Nurse-Family Partnership. Replication across many sites simultaneously, and by a common funder, is labor-intensive and comes with high expectations: Local governments and foundations support evidence-based programs because they trust their investment will yield the same outcomes and cost savings demonstrated in research trials. As a result, ensuring fidelity to the established program model, while allowing for local innovation, is paramount to success. This report provides key lessons for policymakers and funders interested in bringing proven models to a statewide scale, emphasizing the importance of capitalizing on the unique advantage of geographic proximity to build a network of sites whose work becomes greater than the sum of their individual parts. (author abstract)