The discussion on functional foods among scientific communities and EC commissions is mainly focused on definitions and on legislative issues related to the presence on the market of this kind of products. Although many new products continuously appear, the functional food market is characterized by a high rate of failure. To realize a successful functional food, experts having different background should work together following a detailed workplan. In this paper, the problems related to planning and development of functional foods are considered using a step-by-step approach. The strategies for invention and development, formulation and validation of nutritional claims are regarded also illustrating practical examples of functional food development. The concept of food for special medical purposes, intended for individuals who are being treated under medical supervision, is also introduced.