The molecular engineering design and application of polymeric materials for use in delivery systems has evolved into one of the most promising advanced technology areas of polymer science as well as contemporary medical, pharmaceutical, and agricultural science. This volume opens with two chapters providing a perspective on current topics in the field. The remaining twenty-two chapters discuss new and innovative research in the area. They emphasize the role of molecular architecture and associated design and synthesis of new chain molecules and also cover assembling strategies for modulation of release profiles. The authors provide concise accounts of key administration routes and clinical applications. Topics include nanosphere micelles, microspheres, solid implants and injectable liquid gel-formers.