The paper looks at the multimedia dimension of CALL from the point of view of using an authoring tool developed for the production and customisation of (online and offline) multimedia language learning materials. The interaction between learners and teachers in Internet-based pedagogic communication environments is not dealt with. The main emphasis is on the production and customisation of multimedia language learning materials and on the kind of software support needed for their successful embedding in an overall learning and teaching context. The paper also considers the kind of software support needed for the successful embedding of such materials in an overall learning and teaching context. Some of the principles and requirements underlying the development of Multimedia CALL are discussed, but the main focus is on the description of the multimedia learning and authoring software Telos Language Partner. This is a multimedia PC-software designed to incorporate the principles and requirements of multimedia language learning and tutoring discussed in the paper. The software was developed and evaluated with support from the European projects ‘Eloquent’ (Lingua) and ‘Telos’ (Telematics Applications Programme, ET 3005). It supports relevant and authentic language learning activities; intuitive editing functions facilitate the low-cost production, customisation and flexible pedagogical embedding of multimedia language learning contents.