This paper presents the rationale and design process of an authoring interface that enables didactic experts to create or modify eLearning content to make it accessible by learners with special needs. The tool has been designed according to a methodological framework and a set of guidelines for eLearning accessibility previously developed by our group. A key aspect of our framework consists in helping authors to preserve the didactic quality of the eLearning experiences provided to disabled learners (in particular, visually impaired ones) beyond assuring their mere physical access to online materials. A usercentred design process has been adopted to develop a usable prototype of the authoring interface, named aLearning, that we describe below.