The purpose of this study was to investigate the influence of harmonic context on the sightsinging skill of middle school choral music students. A nonrandomized control-group pretest-posttest design with one between-group (treatment method) and two within-group (trial and test context) factors was used. The treatment method used three harmonic contexts: (a) melody only, (b) piano harmony, and (c) vocal harmony. The trial condition had two levels (pretest and posttest), and the test context condition had four levels: (a) melody-only, (b) piano-harmony, (c) vocal harmony/upper with the melody in the higher of two voices, and (d) vocal harmony/lower with the melody in the lower of two voices. A repeated measures ANOVA revealed significant differences for the test context and trial main effects and for the trial by treatment group interaction; subjects obtained the highest sightsinging scores when tested in a melody-only context. Because of the significant interaction between trial and treatment group, one-way ANOVAs were used to test for simple main effects in both trial conditions (pretest and posttest). Although no significant differences were detected in the pretest ANOVA, the posttest ANOVA revealed significant differences among treatment groups. Post hoc analysis indicated that subjects in the melody-only treatment group showed more improvement in sightsinging skill than did subjects in the vocal-harmony treatment group. No difference was revealed, however, between the melody-only treatment group and the piano-harmony treatment group. © 1994, SAGE Publications. All rights reserved.