Significant developments have occurred in the field of professional development (PD) in Australia's vocational education and training (VET) sector in the past 10 years. During the early 1990s, work-based learning (WBL) became the preferred model for PD in the VET sector. Research sponsored by the National Staff Development Committee of the Australian National Training Authority in 1993 identified action learning as an appropriate methodology for structuring national VET sector PD programs. Later research focused on issues such as linking PD programs to national VET policy goals, adopting learner-centered PD approaches, and transforming evaluations of PD programs from efforts designed to satisfy funding requirements to foundations for program improvement. Advocates for basing VET PD programs on WBL based their arguments on the findings of research on adult education, lifelong learning, and learning organizations. A review of the research provides the beginnings of a more detailed descriptive framework for evaluating and researching in the field of PD. The framework draws together theoretical perspectives on andragogy, learning organizations, and theories of critical social science that inform the methodologies of action learning and action research. (Definitions of key terms related to the theoretical foundations of WBL are appended. The bibliography contains 57 references.) (MN)