Massive Online Open Courses (MOOCs) should offer lifelong education opportunities for persons with disabilities. However, most of the current MOOCs are not fully accessible, especially for persons with cognitive impairments and limited learning capacities. To bridge this gap, we have developed an accessible MOOC player following a participatory design process and used it to deliver a course on a mainstream MOOC platform. In this article we describe a field study to evaluate the impact of the player’s accessibility features on the learning experience of persons with disabilities. Following a mixed method approach, we first present the results of a quantitative assessment done with Learning Analytics methods to study the impact of the player on the retention of students with disabilities. Then we present the results of a questionnaire assessment to study the global experience of students in terms of learning performance, usability of the MOOC player, perceived cognitive load and self-determination. Both Learning Analytics and questionnaire -related results confirm our contribution to designing a more inclusive e-learning environment and providing a solid base to improve the accessibility assessment methodology for MOOCs.