Quercus alba, Q. rubra, Q. falcata, and Q. falcata variety pagodifolia seedlings were grown for 105 or 110 days in containers in a greenhouse in a medium with and without vegetative or basidiospore inoculum of the ectomycorrhizal fungi Pisolithus tinctorius and Scleroderma auranteum. At 15 days after planting acorns, nitrogen in the form of sodium nitrate or ammonium chloride was added to each container at the rates of 0.0 or 100 mg nitrogen per seedling. Growth of all Quercus seedlings that were not fertilized was significantly less than seedlings fertilized with nitrate or ammonium nitrogen (100 mg N). Ectomycorrhizal development of all Quercus seedlings that were not fertilized or fertilized with sodim nitrate (100 mg N) was significantly less than seedlings fertilized with ammonium chloride (100 mg N). Ectomycorrhizal development of oak species varied with different mycorrhizal inocula.