The following paper describes the development of an instrument designed to assess middle school students' interest in statistical literacy. The paper commences with a review of the literature as it relates to interest in this context and then proposes a theoretical model upon which the proposed instrument is based. The Rasch Rating Scale model is then applied to student responses to items in the instrument and fit statistics are analysed in order to assess the extent to which these responses conform to the requirements of the measurement model. The paper then presents evidence, including interview data, to support the validity of interpretations that can be made from the proposed instrument. The findings suggest that the proposed instrument provides a theoretically sound measure of middle school students' interest for statistical literacy that will be useful for the evaluation of interventions aimed at developing these students' statistical literacy.