Edge effect is the change in forest structure and composition from the forest edge to the interior and has many conservation implications. We investigated whether sapling density, size, shade tolerance, and species composition, as well as microclimatic conditions, varied depending on proximity to, and aspect of, the forest edge. Across a small (2.25 ha), roughly square, forest fragment surrounded by agriculture, we measured density, size, and species composition of saplings less than 8.3 cm dbh, as well as light intensity, temperature, percent soil moisture, and relative humidity. To test for possible nutrient enhancement on the edges due to agricultural practices, we analyzed soil samples for differences in soil nutrients and pH between the edges and the interior. Both north and south edges had significantly higher sapling density and light intensity and lower average sapling size than the interior of the forest. Average shade tolerance of saplings was lowest on the south edge. Temperature was greatest on the south edge and relative humidity was greatest in the interior. Percent soil moisture, nutrient concentrations, organic matter, and pH showed no significant trends. Our results suggest that light is the most important environmental factor in determining species composition, density, and size of saplings across edge-interior gradients. Our results also show that species compositional edge effects do not penetrate deeply into this mature forest fragment at present, but that they likely penetrated deeper in the forest when the edge was young and narrowed as the edge matured.