This report describes the GRID-Hamilton Depression Rating Scale (GRID-HAMD), an improved version of the Hamilton Depression Rating Scale that was developed through a broad-based international consensus process. The GRID-HAMD separates the frequency of the symptom from its intensity for most items, refines several problematic anchors, and integrates both a structured interview guide and consensus-derived conventions for all items. Usability was established in a small three-site sample of convenience, evaluating 29 outpatients, with most evaluators finding the scale easy to use. Test-retest (4-week) and interrater reliability were established in 34 adult outpatients with major depressive disorder, as part of an ongoing clinical trial. In a separate study, interrater reliability was found to be superior to the Guy version of the HAMD, and as good as the Structured Interview Guide for the Hamilton Depression Rating Scale (SIGH-D), across 30 interview pairs. Finally, using the SIGH-D as the criterion standard, the GRID-HAMD demonstrated high concurrent validity. Overall, these data suggest that the GRID-HAMD is an improvement over the original Guy version as well as the SIGH-D in its incorporation of innovative features and preservation of high reliability and validity.