|The purpose of this study was to further assess the reliability and validity of the Mood Type Indicator, an instrument created by the author to aid in screening for, and the differential diagnosis of, mood disorders. For purposes of measuring reliability, an alternate form method was used; for concurrent validity, the MTI was measured against the Minnesota Multiphasic Personality Inventory-2, and the Beck’s Depression Inventory-II. The results indicated that the MTI with, some additional work, may become a viable instrument. An empirical approach to developing screening instruments for mood disorders was demonstrated. This approach to diagnosis was shown to have utility.