R. C. Abraham's The principles of Tiv, though a teaching grammar which designedly avoids technical terms, contains the most careful and systematic treatment of the Tiv verbal system that has been published, and this and his other books are the only works on Tiv giving tonal details. But his classification of verbs, though based appropriately on their structure and tonal behaviour, is not entirely consistent, nor the most convenient basis for a clear and concise description of the whole verbal system. The present study is based on an analysis of the material provided in Abraham's books—particularly his excellent dictionary—checked and supplemented by several years' practical experience of the language in the field, and more recent detailed research with various informants in London.