The Myers-Briggs Type Indicator (MBTI) is often used in psychotherapy for multiple purposes, including outcome prediction. However, the empirical basis for the MBTI’s prediction of outcome is minimal. In the current study, psychological type (assessed via the MBTI), current Global Assessment of Functioning (GAF), and cognitive-behavioral therapy were used to predict psychotherapy outcome as measured by change in GAF within a sample of outpatient psychotherapy clients (N = 525). Linear regression analyses were used to identify whether the 16 MBTI psychological types and/or which dichotomous attitude and function pairs best predicted psychotherapy outcome. The Thinking-Feeling function was found to be a significant predictor of psychotherapy outcome, such that individuals who prefer Thinking demonstrated greater improvement in GAF than did individuals who preferred Feeling. However, four-letter personality type was not a significant predictor of psychotherapy outcome. Overall, the results indicated that individuals preferring the Thinking function showed greater benefit from cognitive-based CBT than individuals preferring Feeling.