:Some adherends require extensive surface preparation prior to adhesive-bonding while other adherends will form strong adhesive bonds with little or no surface preparation. This paper will attempt to explain the reasons that the above statement is true. Several theories of adhesion will be discussed and the practical application of each will be described. Chemical and physical characteristics of adherend surfaces and several methods for surface analysis will be identified. Finally, an overview of surface preparation methods along with the advantages and disadvantages of each will be described.