This study utilizes data on 157 monocentered SMSAs to examine the theory that increases in the size of peripheral areas of ecological units will be matched with a development of organizational functions in their centers to insure integration and coordination of activities and relationships throughout the enlarged units. Seven detailed components of organizational development in metropolitan central cities and two summary measures of the total organizational components of the central cities are computed from 1960 census data. Correlation and regression analysis are used to determine the influence that increases in both the absolute and relative size of the suburban rings have on the organizational structure of central cities. Findings demonstrate that a balance exists between peripheral growth of metropolitan areas and organizational functions performed in the central cities, and provide strong support for the theory of ecological expansion.