Objective: To test the reliability and validity of the 51-item Field Test Version of the National Eye Institute Visual Function Questionnaire (NEI-VFQ) across 5 common chronic eye conditions. Design: Prospective observational cohort study of persons with 1 of 5 chronic eye diseases who were scheduled for nonurgent visits in ophthalmology practices or had low vision from any cause, and a reference sample of persons without eye disease. Setting: Six university-based ophthalmology practices and the National Eye Institute Clinical Center, Bethesda, Md. Patients: Eligible participants had to have 1 of the following eye conditions: age-related cataracts, age- related macular degeneration, diabetic retinopathy, primary open-angle glaucoma, cytomegalovirus retinitis, or low vision from any cause. Each of the 7 sites also enrolled persons in a reference sample. Reference sample participants had no evidence of underlying eye disease but were scheduled for either screening eye examinations or correction of refractive error. All eligible persons had to be aged 21 years or older, English speaking, and cognitively able to give informed consent and participate in a health status interview. Measurements and Main Results: To provide the data needed to assess the reliability and validity of the 51-item NEI-VFQ, all subjects completed an interview that consisted of the 51-item NEI-VFQ, the Medical Outcomes Study 36-Item Short-Form Health Survey, and at least 1 measure of vision-targeted functional status. Estimates of internal consistency and test-retest reproducibility indicate that the 51-item NEI-VFQ is reliable. Tests of association with other scales and clinical variables support the construct validity of the survey. Conclusions: In this cross-sectional study, the 51-item NEI-VFQ seems to be reliable and valid and should be a useful tool for group-level comparisons of vision-targeted, health-related quality of life in clinical research. Additionally, the psychometric properties of the NEI-VFQ were not influenced by the type or severity of the underlying eye disease, suggesting that the measure will provide reproducible and valid data when used across multiple eye conditions.