Objective: To propose criteria for diagnosis of the night eating syndrome (NES). Method: An international research meeting was held in April 2008, and consensus criteria for NES diagnosis were determined. Results: The core criterion is an abnormally increased food intake in the evening and nighttime, manifested by (1) consumption of at least 25% of intake after the evening meal, and/or (2) nocturnal awakenings with ingestions at least twice per week. Awareness of the eating episodes is required, as is distress or impairment in functioning. Three of five modifiers must also be endorsed. These criteria must be met for a minimum duration of 3 months. Discussion: These criteria help standardize the definition of NES. Additional aspects of the nosology of NES yet to be fully elaborated include its relationship to other eating and sleep disorders. Assessment and analytic tools are needed to assess these new criteria more accurately.