Green composites can be prepared by conventional blending wheat gluten (WG) and other organic or inorganic components using conventional plastic processing equipments followed by thermo-molding of the mixture at elevated temperatures to crosslinking the matrix. In recent years, great attention has been dedicated to the exploitation of natural fibers as reinforcement for plastics, replacing fibers synthetic materials. This book examines the methods for surface modification, which can be physical or chemical, according to superficial modification approach of the fibre. This book also gives a survey about the chemical composition, various mechanical processes for the separation of flax fiber, mechanical properties, physical and chemical treatment methods that improve the flax fiber matrix adhesion, their results and special effects on the various properties of composites. The authors also investigated the preparation and characterization of Mater-Bi/wood flour green composites. The investigation was completed by performing biodegradation tests which allowed assessing the actual biodegradability of the prepared green composites. Other chapters in this book examine the effects of accelerated exposure to seawater on the flexural and impact properties of composites. Densified wood, which can be effectively used as raw material in the production of wood-base green composites, is discussed as well.