Group formation plays a critical role in collaborative learning (CL). It affects the acceptance of group activities by learners and the success of the collaborative learning process. Nevertheless, proposing an effective and pedagogically sound group formation is a very complex issue due to the multiple factors that influence group arrangement. The main goal of this paper is to present an ontology that works as a framework based on learning theories that facilitates group formation and CL design. To validate the usefulness and effectiveness of this ontology we present a method to use it and the results of an experiment carried out with four instructors and twenty participants. The results suggest that our ontology can be used adequately and the concepts represented on it can positively affect the performance of individuals during group learning.