This paper reviews the empirical and theoretical material on urban primacy. The problems with data are highlighted. A measure of primacy is estimated and calculated for most countries in the world. Countries with relatively high rates of primacy are noted. The hyperprimacy of Thailand is discussed as well as the high primacy in middle-income Latin American countries, low-income African countries, and selected European countries. Countries with very low primacy rates are identified. A retheorization of urban primacy is suggested with more emphasis on history, geography and scale.