There is no widely accepted discomfort glare metric for stationary or slow-moving observers in outdoor spaces after dark. This review provides background of 16 relevant discomfort glare models that exist in outdoor environments at night for observers, residents, and pedestrians, for small sources, and non-uniform sources. It includes relevant models and measures comparison studies for this application. It covers general research methods that study discomfort glare – psychophysical, physiological, and behavioral, and model development methods – empirical and visual system-based. The paper discusses the measurement difficulties of glare-relevant parameters in the field and future needs. Recommendations for future research directions and steps forward are offered.