Effective initial teacher education will develop preservice teachers’ disposition towards mathematics and the teaching of mathematics, alongside their mathematical and pedagogical content knowledge. This paper reports on a case study of eight students who participated in an optional mathematics course for preservice primary teachers. Analysis of focus group interviews indicates that students’ dispositions to mathematics and mathematics teaching were influenced by prior negative experiences. Significantly, engagement in the mathematics course contributed both to their self-assessments of their mathematical knowledge, and their professed self-efficacy for inclusive mathematics teaching for conceptual understanding. In this paper, characteristics of the optional mathematics course are identified and implications for initial teacher education are discussed.