Zipf's (1949) generalized harmonic series model of occupational differentiation is tested in91community general hospitals. It was not possible to reject this model in the majority of cases and problems of measurement error make it difficult to claim a firm rejection in the remainder. Relationships among the generalized harmonic series parameters are essentially the same as those reported by Mayhewet al.(1972) for military organizations. Accordingly, from this model of occupational differentiation, we can deduce one of Blau's (1970) major theoretical propositions on the division of labor. The findings of this study broaden the base of empirical support for Zipf's model and Blau's proposition.