The purpose of this study is to trace the development of the major seventh chord from the earliest recorded music through the German School of composition up to the time of Johann Sebastian Bach. The term "major seventh chord" is used to denote the four-tone chord comprised of a major triad plus a tone which is a major seventh above the root. In major keys this chord may be built on the tonic and subdominant degrees of the scale without alterations, and in the "natural" minor on the mediant and the submediant. The full, or structural, name "major-major seventh chord"--used in the present thesis only when it is necessary to distinguish it from other seventh chords with major sevenths-- arises from the fact that the triad (1, 3, 5) is major and the interval between the root and the seventh is major.