This paper examines the challenges of developing and implementing a new national evaluation approach in a complex library funding program. The approach shifts a prior outcome-based evaluation legacy using logic models to one relying on non-linear logic mapping. The new approach is explored by studying the Measuring Success initiative, launched in March 2011 for the largest funded library services program in the US, the Institute for Museum and Library Services formula based Grants to States program. The paper explores the relative benefits of non-linear logic maps and emphasizes the importance of scaling evaluation from individual projects towards clusters of similar library services and activities. The introduction of this new evaluation approach required a new conceptual frame, drawing on diffusion, strategic planning, and other current evaluation theories. The new approach can be widely generalized to many library services, although its focus is on a uniform inter-organizational social network embedded in service delivery. The paper offers a new evaluation perspective for library service professionals by moving from narrow methodological concerns involving measurement to broader administrative issues including diffusion of library use, effective integration of systematic data into program planning and administration, and strengthening multi-stakeholder communication.#2012Conference #eva #GrantstoStates #GovernmentEvaluation #InstituteofMuseumandLibraryServices #LibraryandServicesTechnologyAct