Advanced structures require materials that can provide high tensile strength, modulus, along with good load bearing capacity. Several structural adhesives provide good strength to joints made of different materials. The applications of structural adhesives range from domestic appliances to ships and aircraft along with medical and dental fields. However, an efficient adhesion of the structural adhesives to adherends requires various surface treatment methods to be performed prior to the application of adhesives. These modification methods alter the surface free energy and impart distinct polar groups (‐OH, ‐C=O) on the adherend which act as new receptive sites for adhesion. These surface treatment methods are basically divided into degreasing methods, mechanical abrasion methods (e.g., grit blasting), chemical modification methods (acid‐etching, anodization, etc.), and physical treatment methods (corona treatment, flame treatment, plasma treatment, etc.). This chapter describes various surface preparation methods for the efficient application of structural adhesives along with theories of adhesion, surface treatment evaluation tests, applications, and future scope of structural adhesives.