While the benefits of teacher involvement in designing technology enhanced learning are acknowledged in the literature, far less is known about shaping that involvement to yield those benefits. Research is needed to understand how teachers learn through design; how teacher design activities may be supported; and how teacher involvement in design in various ways impacts the quality of the artifacts created, their implementation, and ultimately, student learning. Existing conceptual foundations for teacher design work are urgently in need of bolstering, and will definitely play a critical role in the future of instructional science. This special issue presents the work of a large collaborative group of researchers, which, since 2012, has explored divergence and convergence among multiple research projects involving teachers as designers of technology enhanced learning (TaD of TEL), and has endeavored to extend existing knowledge to strengthen TaD of TEL as a field of research.