This book is the inaugural volume a series entitled Polymeric Foams: Technology and Applications. Generally, thermoplastic and thermoset foams have been treated as two separate practices in industry. Polymeric Foams: Mechanisms and Materials presents the basics of foaming in general build a strong foundation to those working in both thermoplastic and thermoset foams. The book addresses scientific principles behind polymeric foaming and presents foaming chemistry and physics, resin and blowing agents, and foaming mechanisms in separate chapters, thus providing an overall and fundamental understanding of foaming for polymeric foam products and processes.