Background: The purpose of this study is to define treatment response and remission cut-point scores for the Beck Depression Inventory-Second Edition (BDI-II) when used to monitor seasonal affective disorder (SAD) treatment. Methods: Data from two published randomized clinical trials for SAD were utilized to complete a ROC analysis to define response and remission thresholds for the BDI-II. The Structured Interview Guide for the Hamilton Rating Scale for Depression-Seasonal Affective Disorder Version (SIGH-SAD) was used as a reference standard. Data from the two trials included BDI-II and SIGH-SAD scores for patients at baseline, 6 weeks (post-treatment), and 1 year (next winter). Results: BDI-II score of <= 9 was the derived criterion for remission of SAD, and BDI-II score decrease of 50% from baseline was the criterion for treatment response. Limitations: Study participants were primarily female (94%) and Caucasian (80%) so demographic diversity of the sample was limited. Conclusion: This study validated BDI-II scores compared to the SIGH-SAD reference standard. The BDI-II has greater potential for widespread use by clinicians than the SIGH-SAD to monitor SAD patients because it is a brief self-report instrument that can be conveniently administered in the waiting room. (C) 2011 Elsevier B.V. All rights reserved.