This volume presents the results of numerous worldwide studies focusing on the implementation of natural polymers as engineering plastics and the use of their inherent properties. It discusses the processing and, more extensively, the applicati on of natural materials (cellulose and protein-based) as reinforcements for polymer composites. The structural, morphological, and thermal characteristics, as well as the mechanical behavior of the obtained materials are covered comprehensively. In addition, the book includes case studies and results of commercial relevance. All natural polymers used in the blending or reinforcement of synthetic polymers are discussed in an attempt to cover the isolation, pretreatment, blending, and manufacturing of the respective materials.