The content of the book can be divided into two different types of composites based on the nature of polymer used: i) Hydrocarbon based Polymer (Polypropylene, PP) and fly ash, ii) Functionalized-Polymer (Polyvinyl alcohol, PVA) and fly ash. Composites of Gladstone fly ash (GFA) reinforced isotactic semicrystalline PP were prepared by injection molding at 210 øC incorporating 20, 45 and 60 wt% GFA. Tensile tests were carried out at 25, 50 and 70 øC. Modulus of elasticity of all composites at all temperatures was higher than that of the corresponding PP samples ? the gain ranged between 10 to 60 %. The strength of the composites had a mixed trend. Biodegradable composite films of PVA and Swanbank fly ash (SFA) spanning 5, 10, 15, 20 and 25 wt% concentrations were prepared by casting aqueous solutions. Four different classes of composite films were prepared by PVA and SFA. The tensile strengths of the composite films were increased proportionally via addition of SFA. The strength of the film was enhanced by 193 % with 20 wt% SFA compared to the neat PVA control. Further addition of SFA deviated from the linear trend.