Revision with unchanged content. Dealing with classroom diversity while trying to engage students in meaningful and rewarding instructional activities has proven to be a real challenge for both researchers and practitioners in the field of education. The overall purpose of this longitudinal study was to investigate the interaction between the learning, and the Design-Based Research (DBR) processes using a cognitive flexibility hypertext (CFH) as the object of research. The first major focus was on the impact of the CFH on students’ learning. A second major focus was the structure of the DBR process, especially the interplay between research and design when supporting an improved learning process. While the research and design findings reported for the two consecutive years represent in and of themselves significant contributions to the field of DBR, the researcher’s reflective analysis found a theoretical link between the DBR process and the model Expansive Developmental Research proposed by Activity Theory. The book is addressed to educational researchers, graduate students, and educational practitioners interested in successfully implementing innovative technology-driven designs in complex classroom contexts.