An interval measure of modernization is devised, applicable to pre- and post-industrial societies. The modernization of a society denotes the recency of its form of social organization in human (pre-)history. Murdock and Provost’ (1973) ordinal markers of pre-industrial modernization are updated to be interval measures observable today. The recency (in years) of marker gradations is not currently observable in prehistory, but marker gradations are observable in databases such as the pre-industrial “Standard Cross-Cultural Sample” and the World Bank’s post-industrial “World Development Indicators.” The modernization magnitude of a society is defined to be the mean of the standardized, updated, marker variable measures on the society. The new modernization construct and measure may be used for many purposes, including the testing of behavioral theory spanning post- and/or pre-industrial societies.