This article reviews generally the principles of bonding composite structures. The advantages and disadvantages for adhesive bonding of composite materials are summarized. The commonly employed adhesives, surface preparation processes, and production methods are identified and discussed. Adhesives are commonly used to bond composites for a number of practical and economic reasons. Most common composite materials are based on a matrix consisting of thermosetting resin (e.g., epoxy, polyester, phenolic) and glass fiber. However, several new types of composites are gradually entering the market. These are based on advanced fibers and / or thermoplastic resin matrices. Special focus is given to modern composite materials such as the thermoplastic composites that are now being used in certain applications. These are often where high volume and economic considerations predominate such as in the automotive and outdoor decorative paneling industries. Processes other than adhesive bonding can be used with certain thermoplastic composites and these are also reviewed.