The current movement towards multilingualism and multiculturalism in South Africa has placed language at the centre of all educational activity. With the implementation of the outcomes-based Curriculum 2005, the emphasis is on appropriate learning support material, and the learning programmes are seen as guides that allow teachers to be innovative and creative in designing instructional and learning material. The fact that Afrikaans was one of three compulsory language subjects at a school in the Soweto area motivated researchers of Technikon South Africa to embark upon an outreach project. The latter entailed a remedial programme to address the lack of Afrikaans language proficiency of the Grade 12 learners at this school. My role as the remedial teacher and my subsequent responsibility for the development of appropriate and relevant learning material for the intervention provided the impetus and motivation for this research. The aim of the study was to determine the criteria for developing materials, in order to develop the proficiency in Afrikaans of Grade 12 additional language learners. The intervention took the form of an ongoing action research cycle. The magnitude of the proficiency dilemma in this study was revealed by a pre-intervention assessment. Apart from the learners’ poor functional Afrikaans literacy, it also became apparent that the influence of affective variables in additional language learning should be considered. The literature survey undertaken to articulate the relevant information about Communicative Language teaching (CLT) emphasised the kind of teaching necessary to develop proficiency in an additional language. In addition, the exploration of the influence of affective factors on additional language teaching and learning allowed a better understanding of the learners’ needs and ensured a learning-centered approach. In the process of materials selection, adaptation and development, it was necessary to relate learning principles and procedure to theory, research methods and classroom practice. Reviewing the literature on issues such as designing and developing materials contributed to a pragmatic approach to materials development, and assisted in establishing the criteria for the development of appropriate materials. The study has attempted to show how to design appropriate and relevant teaching materials guided by a set of criteria. The implementation of the materials in the classroom integrated theory and practice. Thus in practice, through different action research cycles, the developed materials were shown to comply with the theoretical criteria to establish their effectiveness, and refined to suit the proficiency level of the particular learners. Finally, critical reflection resulted in a redesigned set of materials for Afrikaans as an additional language. The post-intervention assessment showed that there was indeed an improvement in the learners’ proficiency levels and that the average grade of their proficiency levels improved. Other findings suggested the probability of a positive attitude change in the learners. Thus, it can be concluded that the intervention may be judged as having been relatively successful.