Digital library interaction evaluation has, by nature, a user centered perspective, which directs the scientific research to the benefit of the user and narrows the research parameters. In this paper we propose a new framework for the evaluation of interaction and we introduce the concepts of usefulness, usability and performance as the main contributing factors for the creation of a rational and successful interaction. The framework attempts to trace and highlight some of the interaction evaluation requirements and parameters, in order to be sufficient in many different contexts.