Subtropical coastal sand dune ecosystems have been greatly altered by agricultural use, invasive exotic encroachment, urban development, and beach raking, rendering several plant species endangered or threatened. Restoration planning of this ecosystem will benefit from a comprehensive study on how environmental variables change across the coast-to-inland gradient of this ecosystem and it is therefore presented here. We also examined the relationship between the environmental characteristics and plant species composition across the gradient. We used the two largest extents of remaining dune ecosystem on the southeastern coast of Florida, where relatively intact populations of endangered species occur. Vegetation and environmental data were collected from 97 3 × 8 m plots in two sand dune parks along the coast–inland gradient. Soil moisture, most nutrients, cation exchange capacity, and organic matter accumulation increased with distance from the coast, whereas pH and salt spray decreased. The number of species per plot was higher at further distances from the coast at one site only, and higher woody cover was associated with less species diversity at the other site. Canonical correspondence analysis revealed the importance of P, Mg, Ca, pH, cation exchange capacity, organic matter, estimated nitrogen release, and salt spray in affecting vegetation zonation. We conclude that soil chemistry is the most determinant factor of community zonation in these subtropical dunes. Restoration planning should be site specific because of the differences in environmental factors between the two study sites.