Supplemental Instruction is a program designed to support students in their learning process. The program consists of advanced students supervising new students, where the purpose is to improve students' performance and reduce the risk of interruption of studies. Supplemental Instruction was established almost 50 years ago and is used today in universities around the world. This book examines different aspects of SI in organizations and leadership, including surveys of Supplemental Instruction programs in Europe, how SI sessions should be organized, the degree to which SI improves retention rates and exam results, SI and learning leadership and leadership development, benefits of being a member of an SI team and employability, SI implementation in healthcare education and virtual students' attitudes towards SI online. The book is aimed at anyone who is concerned about study quality in higher education. The contributors are researchers and lecturers at various universities from several countries. The book is part of a trilogy on Supplemental Instruction, where the themes for the other books are "Digital Technologies" and "Student Learning Processes". The editors of the trilogy are Abbas Strømmen-Bakhtiar (Professor), Roger Helde (Associate Professor) and Elisabeth Suzen (Associate Professor), all three at Nord University, Norway.