Over the past ten to fifteen years the international scene of research on learning and instruction has witnessed the emergence of important and promising developments. New theoretical frameworks, design principles, and research methodologies focusing on the construction, implementation, and evaluation of powerful learning environments have been put forward, coming from three intersecting subdomains within the broader field of research on learning and instruction - namely instructional psychology, instructional technology, and instructional design. Although it is obvious that the developments in those three subdomains are characterized by similarities and convergencies, there are still important differences. Therefore, there is a great need for scientific debate and attempts to integrate, or justify, the contrasting theoretical frameworks, methodological approaches, and empirical outcomes. A European research network, coordinated by the Center for Instructional Psychology and Technology of the University of Leuven, has been set up to work towards this end. The present volume is the first collective output of this European research network, and focuses on unravelling and identifying basic component and dimensions of powerful learning environments. It is based on the presentations and discussions that constituted the "piece de resistance" of a first meeting of the research network.