This book explores foundational theories that have been applied in open and distance education (ODE) research and refined to reflect advances in research and practice. In addition, it develops new theories emerging from recent developments in ODE. The book provides a unique and up-to-date source of information for ODE scholars and graduate students, enabling them to make sense of essential theory, research and practice in their field, and to comprehend the gaps in, and need for further enquiry into, theoretical approaches in the digital era. It also offers theory-based advice and guidelines for practitioners, helping them make and justify decisions and actions concerning the development, implementation, research and evaluation of ODE.