Part I of this article has outlined the conditions under which corrosion can occur and the approaches for preventing or controlling corrosion attack. One of the approaches is to use protective coatings to prevent the corrosive environment from reaching and reacting with the substrate metal. These coatings may be organic or inorganic in composition, or a combination of both. In this article the focus has been on organic coating systems and how they may be modified to provide better corrosion resistance through the use of additives. Inorganic additives traditionally have been used to improve the stability and corrosion resistance of paint systems, and these are discussed in Part II of this article. Barrier coatings incorporate particles or lamellae to effectively increase the diffusion pathway of corrosive ions to the metal surface and delay corrosion attack. Reactive particles may be incorporated into coatings to react with the corrosive ions and prevent them from reaching the metal/coating interface. Some additives facilitate the oxidation of the metal surface and passivate it, preventing corrosion from occurring. Sacrificial additives are metals, such as zinc, that corrode preferentially to the metal substrate and protect it by an electrochemical (galvanic) action. Other additives may dissolve slowly and provide an inhibiting action to protect the metal. Examples of each of these types of additive have been provided, along with some recent developments. In Part III of this article, a similar discussion is provided, but the additive chemicals are organic compounds, many of which enable more environmentally compliant coatings to be formulated. In addition, the relatively recent research on the use of conducting polymers (organic metals) to protect metal surfaces is discussed. Some polyaniline-based additive packages are now available commercially in small quantities. The use of self-assembling monolayers to provide thin barrier films with corrosion protection properties is a new area of research on organic coatings with tailored properties. Finally, it should be remembered that, for these types of coatings to be accepted in industry and commerce, they must be robust systems, available in sufficient quantities at an acceptable price, and provide equivalent or better performance in the field. The ancillary equipment used to apply them also must be available. This may require the modification of currently available equipment or the development of the new equipment appropriate to the coating system being offered for sale.