In recent years, nuclear security has gained prominence on the international security agenda. Driven by post 9/11 anxieties and the politicization of fears regarding nuclear terrorism, concerns in this area have spawned a wealth of initiatives, which seek to counter this threat. Principal among these have been efforts to promote nuclear security education and infuse teaching and learning in this sphere with a more holistic understanding of the subject, its relevance and its implications. Against this background, this article sets out the findings of empirical research into the impact of nuclear security 'train-the-trainer' professional development courses on the practice of an emerging cadre of nuclear security educators. In particular, the paper explores the value of this model as a means of establishing sustainable communities of practice in the context of nuclear security education.