Increased stressors on coral reefs in recent decades have led to a decline in coral populations throughout the Florida Keys Reef Tract (FKRT). In contrast, the relative abundance of Porites astreoides has increased throughout the western Atlantic due to its “weedy” life history strategy. Compared to reef-building species, P. astreoides is relatively resistant to some environmental stressors and, due to its mixed reproductive strategies, its populations often recover relatively quickly after disturbances. Whether P. astreoides will continue to be a “winner” on western Atlantic reefs, however, will depend on its ability to acclimatize and/or adapt to changing environments in the future. The potential for high rates of selfing and other asexual reproductive modes observed in some studies suggest that many colonies of P. astreoides may be clones rather than genetically distinct individuals, which could limit the species’ capacity for adaption. Population genetics can provide clues for understanding regional species ecology and diversity and help identify how populations may change in the future. In this study, we determined the genetic diversity of 40 P. astreoides samples at four locations along the FKRT using previously designed microsatellite markers. Our results suggest that clones were relatively rare at our sites, and the FKRT most likely contains a single, well-mixed genetic population of P. astreoides, with high levels of gene flow in the region. This suggests that P. astreoides will likely continue to be resilient to future stressors while the larger causes of anthropogenic stressors are addressed.