This paper presentation describes the initial stages in a programme of work investigating the decision making processes that take place around the choice of symbolic vocabularies for children and young people who use, or could use, aided communication. The overall aim of this work is to inform the decision making processes in the selection of communication systems with the hope that this will also improve the design and efficacy of such systems. The aim of this paper is to give an overview of the issues relating to decision making regarding symbolic vocabularies for aided communication. The paper will present an initial theoretical structure of communication and language relating to the use of symbol vocabularies derived from a review of the literature. The paper will also present an initial characterisation of existing symbol vocabularies. These two elements of work provide an initial foundation from the two perspectives of the user and the system on which the proposed future investigations can build. This presentation will report on on-going work and conclusions will be tentative and exploratory and aim to foster discussion with the audience.