This article, the first in a two-part series, describes and critically evaluates major contributions in the last seventy years of scholarship on the relationship between Ioudaios ('Jew' or 'Judaean') and other group labels. The first section examines the common suggestion that Ioudaios was an outsider label, and 'Israel' an insider label. The second section surveys explanations of the relationship between Ioudaios and other terms such as 'Galilaean', 'Idumaean' and 'Ituraean', evaluating them in light of the evidence from Josephus. The conclusion sketches the decline of religion and rise of ethnicity as interpretive categories in scholarship on Ioudaios, and raises questions about the meaning of the term that require further discussion. The second article in this series will analyse the use of religion and ethnicity in scholarship on the meaning of Ioudaios, and evaluate the debate over the term's English translation.