This book investigates paradigms of person - both independent pronouns as well as bound person marking. Based on empirical and theoretical grounds, the author argues that the notion 'number' has to be redefined to deal with the cross-linguistic variation of person marking. Equipped with a new definition, a typology of the paradigmatic structure of person marking is presented, incorporating data from around 400 languages. Nothing appears to be impossible for the paradigmatic structure, although some patterns are clearly more probable than others are. Starting from the more commonly occurring patterns, the diachronic dynamics of paradigmatic structure are investigated by comparing close relatives that differ slightly in the structure of their person paradigms.