Virtual worlds are an important tool in modern education practices as well as providing socialisation, entertainment and a laboratory for collaborative work. This paper focuses on the uses of virtual worlds for education and synthesises over 100 published academic papers, reports and educational websites from around the world. A taxonomy is then derived from these papers, delineating current theoretical and practical work on virtual world usage, specifically in the field of education. The taxonomy identifies rich veins of current research and practice in associated educational theory and in simulated worlds or environments, yet it also demonstrates the paucity of work in important areas such as evaluation, grading and accessibility. (Contains 1 table and 5 figures.)