The paper analyzes the city-forming propensities, the service factors, in the Turkish central place hierarchy at the regional and national levels. It is built on the premise posited by Christaller that a functional relationship exists between the population of a central place and its complementary area. Following Beekmann and MePherson and utilizing data from a countrywide survey, city-forming propensities are calculated for the sixteen-functional regions and the nation to see whether any systematic variation occurs between the k patterns. The basle Beckmann-McPherson model is modified to take into account of the variable K hierarchy of the Turkish system and the non-central (non-nodal), primarily agricultural, activities in the Ist order central places. To take account of the latter factor, "notional populations" are calculated for the Ist order centers, and these, rather than the actual populations, are used in finding the sets of city-forming propensities. In the 2nd part of the paper, the factors behind the variations between the regional k values are analyzed. Population density, per-capita income and the employmentactivity-structure, particularly the extent of manufacturing employment, are found to be the main determinants of the variation in k values both within and between regions.