Owing to the availability of birth and population data, it was possible to study the variation of standardized rates of birth per 1,000 women aged fifteen to forty-four in a metropolitan city and to determine the extent to which specific socioeconomic variables were associated with this variation. Through the use of a mapping technique, spatial variation was tested; through the use of zero order, partial and multiple correlations, a test was made of the association of birth rates and specific socioeconomic variables. In general, it was found that births increase in rate with an increase in miles from the center of the city; that although this pattern of increase occurred, its gradiency was not so regular as has been shown by the use of other types of social phenomena in other studies. The degree of relationship as shown by correlating standardized birth rates and specific variables differed widely. There was a negative association of these rates and the socioeconomic variables of (a) per cent women fourteen years of age and over employed, (b) per cent professional workers, (c) per cent white-collar workers, (d) median educational level, and (e) median rental rates. There was a positive association of birth rates and (f) per cent workers as craftsmen and operatives and (g) per cent homeowners. However, tests showed per cent women employed and per cent professional workers as the most reliable variables associated with the phenomena of birth. Data concerning the distribution of married women were not available. Therefore, this factor could not be controlled.