Fifty-one tonal and atonal classical melodies were evaluated by 29 students on 10 bipolar adjective scales that focused on emotional evaluation along four factors: valence, aesthetic judgment, activity, and potency. Significant predictors for each factor were obtained through ridge regression analyses. Predictors were quantified characteristics of each melody: the distribution of intervals according to interval size, the mode, and tonal strength (C. L. Krumhansl, 1990). Valence was best predicted by mode. Aesthetic judgment was predicted by the interval distribution and by tonal strength. Melodies judged pleasant contained more perfect fourths and minor sevenths and fewer augmented fourths; they were also high in tonal strength. Activity and potency were best predicted by the interval distribution. Activity, a sense of instability and motion, was conveyed by a greater occurrence of minor seconds, augmented fourths, and intervals larger than the octave. Potency, an expression of vigor and power, was marked by a greater occurrence of unisons and octaves. Thus the emotional expression of a melody appears to be related to the distributions of its interval categories, its mode, and its tonal strength.