Models of stratospheric chemistry have long predicted the existence of N2O5 in the stratosphere (1). A previously measured upper limit suggested that the lower stratosphere contained less than 1/10 of the N2O5 predicted (2). This serious discrepancy has eroded faith in predictions of changes in stratospheric composition due to man's activities. These new observations of atmospheric emission at N2O5 wavelengths suggest a mixing ratio of 1.1¿0.5¿10-9 between 30 and 40 km. This value is fully consistent with model predictions.