Publisher Summary The chapter discusses the legal aspects for functional feed ingredients in the European Community (EC). Livestock production is important for the European economy. Adequate nutrition of animals is achieved by balanced diets and by the inclusion of compounds with specific functional effects. Feed additives have to undergo admission procedures that ensure efficacy and safety. In companion animals, trends can be observed towards foods with proven or assumed health benefits. Pet food is in this aspect similar to human food. Feedingstuffs that are brought onto the market with “health claims” must be admitted as feedingstuffs for particular nutritional purposes. The authorization procedure for the placing on the market of genetically modified food and feed includes feed additives consisting of, containing or produced from, genetically modified organisms (GMOs). These additives can have technological, sensory, nutritional or zootechnical impact. Specific groups are coccidiostats and histomonostats. Depending on the claim, the intended use and their chemical and physiological properties, feed additives are categorized into the following groups: (1) chemically defined substances such as preservatives, vitamins, acidity regulators, trace elements, (2) living microorganisms, (3) spores of microorganisms, (4) enzymes. Feed additives are substances, microorganisms or preparations that are added to feed or water. Feed additives are used to favorably affect the characteristics of feed, the characteristics of animal-derived products, or the color of ornamental fish and birds. Feed additives are used to fulfill the nutritional needs of animals, to reduce the negative impact of animal production on the environment, to have positive effects on animal production, performance or welfare. This is particularly accomplished by effects on the gastrointestinal microflora, by enhancement of the digestibility of feedingstuffs, or by a coccidiostatic or histomonostatic effect. The chapter discusses several regulations related to these additives.