In this book, Nizar Abdelkafi defines variety-induced complexity from the perspectives of the company, supply chain and customers. The author develops a sequence model and a key metrics system for the management of internal complexity, proposes a matrix-based tool that identifies the causes of complexity in mass customization supply chains and conducts an explorative study at a Germany-based company. Furthermore he identifies features, to use in online configuration systems to reduce the complexity that customers face during the product selection process.