Lifelong learning is a familiar concept in ordinary conversation and in public policy discourses. Though the history and various meanings of lifelong learning are noble, it has in more recent times been identified with functional interests, economic goals, and one-dimensional interpretations. This chapter identifies the genesis and grounding of lifelong learning in psychology and adult education, disciplines that establish the foundations for our understanding of learning. Classical and current learning theories are outlined, including behaviorism, cognitivism, and constructivism from psychology. Adult education learning theory contributes andragogy, self-directed learning, experiential learning, multiple intelligences, and transformative learning. Insights from critical pedagogy are added in order to suggest models of lifelong learning that transcend functional models. This more critical interpretation contributes to a better understanding of lifelong learning that has an interest in enhancing communities and society and promoting the democratic and emancipatory goals of education.