Appropriate professional development, including that initial teacher training, is regarded as a cornerstone of the development of inclusive education. This research is concerned with prospective teachers' conceptualisations of terms such as "disability" and "special education". Activity theory is proposed as a lens through which to consider the complexities involved. In the context of the English systems, this research, using data collected through word association and analysed using activity theory, explored the trainees' conceptualisations. The findings highlight both heterogeneity and homogeneity within a cohort of students, changes over time and implications for those involved in teacher education. (Contains 5 figures and 3 tables.)