The effect of carbon quality on potential denitrification of stream sediment was examined using leaf leachate of dominant species in a suburbanizing basin in southeastern New Hampshire.  Senescent leaves from red maple, white pine, red oak, and lawn grass were collected in Fall 2006, and 10 grams of dried litter were leached for 24 hours in 2L of water.  DOC concentration from leachate ranged from ~16 mg L^-1 for Pine to ~360 mg L^-1 for maple, with oak and grass falling in between.  Denitrification enzyme assays were amended with NO₃ and performed under anaerobic conditions using the acetylene block method.  After normalizing for DOC concentration, preliminary results show that pine leachate had the lowest denitrification potential by ~50% while grass showed the highest (p=0.02; Tukey’s multiple comparison test).  Oak and Maple were similar and intermediate between pine and grass (p=0.96; Tukey’s).  CO₂ produced was similar among species, suggesting that denitrification may be more sensitive to carbon quality than microbial respiration.  DOC quality as well as concentration appears to have important effects on N losses via denitrification in suburbanizing watersheds.