Plastics find many uses in industry due to their processability and unique mechanical properties. Unfortunately, some of the same features that make polymer properties unique, such as solvent resistance and smoothness, make them difficult to use in adhesive bonding. This situation occurs because those same properties are commensurate with low surface energy and minimal chance for interfacial mechanical interlocking. This presentation describes the basic science underlying the reasons why adhesive bonding of plastics is often difficult. The presentation also describes numerous methods of polymer surface preparation. Where possible, the mechanism of action of the surface preparation is discussed.