This document summarizes a study exploring factors that facilitate or inhibit the long-term impact (sustainability) of projects funded under the European Lifelong Learning Programme. The study uses qualitative interviews with project coordinators to identify factors within four areas: (1) the internal organizational environment of the project, (2) how the project interacts with the external environment, (3) how the project seeks to influence the external environment, and (4) the influence of the programmatic funding environment. The study aims to generate hypotheses about sustainability that can be validated through further research and inform policy and management practices to increase the effectiveness of the Lifelong Learning Programme.