Measurements of marginally unstable electron distribution functions and high-frequency plasma waves were made on a sounding rocket flight through a quiet auroral arc. The waves appeared near the electron plasma frequency and had a large parallel electric field component such that k∥>k⊥. The appearance of these waves was correlated with the presence of marginally unstable parallel electron distributions. Analysis has shown that the waves were produced by ∂fe/∂v∥ >0 rather than the small ∂fe/∂v⊥>0 features. Wave levels and growth rates inside the arc were small, and nonlinear wave-wave and wave-particle interactions appear to have been minimal.