The Perseus Digital Library, (PDL) is one of the primary digital resources for the humanities. Under continuous development since 1987, the project has included an ongoing evaluation component that aims to understand the effects of access to digitized source materials in the humanities. A summary of the PDL genesis and current status is given and the multifaceted and longitudinal evaluation effort is described. A brief synthesis of results is provided and reflections on the evaluation along with recommendations for DL evaluation are given.