The problem and the solution. Adult learning is a core concept in support of basic human resource development concepts, such as performance improvement, continuous quality improvement, knowledge management, organizational learning, change management, learning organizations, and a myriad of other initiatives. Yet adult learning is not understood very well. In spite of decades of research, adult educators and HRD practitioners still have imperfect understandings of adult learning, and researchers continue to search for a unitary theory of adult learning. This issue of Advances makes clear that how adults learn is, at least in part, influenced by their worldview. This realization, along with the extensive diversity of worldviews, calls for a new perspective about adult learning in the workplace, among practitioners, theoreticians, and researchers.