This editorial describes the increasing use of extenders that are based on naturally occurring materials. These can be used as additives or base polymers. Polymeric waste can also be used as a cost-effective and environmentally friendly component in adhesives systems. Extenders are substances which usually have some adhesive properties and are added to reduce the concentration of other adhesive components and, thereby, the cost of the overall formulation. Extenders may also have positive value in modifying the physical properties of the adhesive, although their primary purpose is to reduce cost.