Gastropods of the family Strombidae are well-known and important constituents of modern tropical marine communities. The biology of several modern species has been throughly investigated due to their economic value as a human food resource. Unlike many gastropods, strombids undergo pseudo-determinate growth; they therefore present intriguing possibilities for investigation of size-related patterns of change. Unfortunately, they also display a wide degree of intraspecific morphologic variation, making reliable determination of species identity difficult. In this paper, we examine members of this family from the late Miocene and early Pliocene deposits of the Cibao Valley, located in the northwestern portion of the Dominican Republic on the Caribbean island of Hispaniola. After brief descriptions of the general geologic setting of the Cibao Valley and the biology of modern strombids, we delineate the observed geographic and stratigraphic ranges for species of Strombus and Lobatus in the Cibao Valley. At least 11 species of strombids have been reported from the Dominican Republic. Based on the high degree of intraspecific morphologic variation common in these genera and upon examination of individual specimens, we synonomize several older names and recognize only five species in two genera from the Cibao sequence: S. bifrons, S. proximus, L. haitensis, L. galliformis, and L. dominator. We describe some aspects of strombid paleoecology and summarize spatiotemporal patterns of distribution. Differences exist between modern strombid populations and our collections of Miocene Dominican ones; strombids of the Cibao Valley are in general smaller and appear to have occupied somewhat different habitats than those of their modern relatives.