There is little dispute that lifelong learning is essential to the further development of the knowledge society. Nonetheless, lifelong learning is not reaching its full potential because the currently used approaches to lifelong learning are too fragmented and, often, formal approaches to education and learning are simply 'translated' from initial secondary and higher education to the field of lifelong learning. This article discusses an integrated framework for carrying out research on lifelong learning. The framework is built on two dimensions: (1) the specific-generic dimension, linking contextualized research findings in the field of lifelong learning to generic issues and principles; and (2) the individual-collective dimension, linking research findings on the personal and professional development of individual lifelong learners to the level of organizations, cities, and regions. Moreover, three integrative features of research on lifelong learning are identified: Developed approaches should be (1) responsive to societal and technological changes and associated changes in required competencies; (2) flexible in order to serve highly heterogeneous groups of lifelong learners; and (3) sustainable to be of value across the whole lifespan. Finally, research and practical implications of the presented framework are discussed.