ABSTRACT:In distance education and training, tutors play a fundamental role as they act as a facilitator of the learning process, particularly through their evaluation of the progress made. In this paper, we provide an overview of tutoring in e-learning contexts and describe the main functions that should be assumed by a tutor. We then analyze all activities performed by tutors and establish conceptual models based on the Unified Modeling Language. The models promote an in-depth analysis and a detailed description of the functions needed to tutor on-line courses. These models may not only be used as guidelines for tutors but also as a general schema to assess their work. Evaluation and validation of these models have been accomplished by a questionnaire that has been designed and distributed to learners in the framework of a tutored e-learning experiment. ß