What are the relevant values to assess a scientific theory? This question remains hotly debated. Thomas Kuhn (1977) suggested a list of five desirable values that scientists should take into account in theory choice. That list included accuracy, consistency, scope, simplicity, and fruitfulness. Since then, several philosophers have proposed many lists and discussed the meaning and role of these values. Surprisingly, little attention has been paid to fruitfulness. In this paper, I suggest a new approach to assess fruitfulness, focused on the methods and tests used by a research program to formulate and validate hypotheses and predictions. Moreover, I make use of a specific case study, i.e., the Adaptationist Programme, to show how this approach improves the understanding and assessment of fruitfulness.