Recent assessments of atmospheric deposition in North America note the increasing importance of reduced (NHx = NH₃ + NH₄⁺) forms of nitrogen (N) relative to oxidized forms.  This shift in in the composition of inorganic nitrogen deposition has both ecological and policy implications. Deposition budgets developed from inferential models applied at the landscape scale, as well as regional and global chemical transport models, indicate that NH₃ dry deposition contributes a significant portion of inorganic N deposition in many areas.  However, the bidirectional NH₃ flux algorithms employed in these models have not been extensively evaluated for North American conditions (e.g, atmospheric chemistry, meteorology, biogeochemistry). Further understanding of the processes controlling NH₃ air-surface exchange in natural systems is critically needed. Based on preliminary results from the Southern Appalachian Nitrogen Deposition Study (SANDS), this presentation examines processes of NH₃ air-surface exchange in a deciduous montane forest at the Coweeta Hydrologic Laboratory in western North Carolina.  A combination of measurements and modeling are used to investigate net fluxes of NH₃ above the forest and sources and sinks of NH₃ within the canopy and forest floor.  Measurements of biogeochemical NH₄⁺ pools are used to characterize emission potential and NH₃ compensation points of canopy foliage (i.e., green vegetation), leaf litter, and soil and their relation to NH₃ fluxes.  Differences in bidirectional flux modeling results using generalized versus site-specific parameterizations of foliage versus soil processes are addressed along with recommendations for model improvements.  Next steps for further processing of SANDS datasets are also discussed.