Book excerpt: The Instructional Design Knowledge Base: Theory, Research and Practice provides ID professionals and students at all levels with a comprehensive exploration of the theories and research that serve as a foundation for current and emerging ID practice. This book offers both current and classic interpretations of theory from a range of disciplines and approaches. It encompasses general systems, communication, learning, early instructional, media, conditions-based, constructivist design and performance-improvement theories. Features include: rich representations of the ID literature concise theory summaries specific examples of how theory is applied to practice recommendations for future research a glossary of related terms a comprehensive list of references. A perfect resource for instructional design and technology doctoral, masters and educational specialist certificate programs, The Instructional Design Knowledge Base provides students and scholars with a comprehensive background for ID practice and a foundation for future ID thinking.