Because depressed patients commonly experience reductions in motivation and energy, both as symptoms of their disorder and as side effects of pharmacotherapy, it is important to identify interventions that can restore their vitality. The Motivation and Energy Inventory (MEI) was recently developed to facilitate the evaluation of such efforts both in depression research, as well as in other therapeutic areas where vitality is an important issue. The constructs addressed by the MEI were identified through a combination of literature review, consultation with experts, and patient focus groups. Potential problems identified during cognitive testing and addressed in subsequent revisions related to the instructions, reference period, response scale sizes, and response scale labels, as well as a number of item-specific issues. Most recently, the data from two randomized, placebo-controlled clinical trials were utilized to evaluate the psychometric properties of the new questionnaire. In general, the data collected during the first and second trial were used for exploratory and confirmatory analysis, respectively. Consistent with the measurement model of the MEI, the psychometric results confirm that the instrument has three factors generally addressing physical energy, mental energy, and social motivation. Furthermore, these results provide evidence for the internal consistency, construct validity, and responsiveness of all three MEI subscales. Additional work is currently underway to examine test-retest reliability and establish minimal clinically important difference values forthe MEI subscales.