Circum-Caribbean nations are experiencing the fastest urban growth rate in the world. If investigation of city size distribution can be of any relevance to national development policy, chances are that it will be the most useful where the urban hierarchy is still taking shape. Three types of cities Systems are identified: « Extreme Primate », « Moderate Primate » and « Lognormal ». These urban structures variations through time and space are commented upon as being related to such factors as: a varying number of cities; peculiar political or historical conditions; the impact of an international function on the capital city; and the influence of the physical environment.