This document uses musical theatre repertoire to both reinforce and extend music-theoretical concepts typically taught in undergraduate theory sequences. Three such concepts—modulation, form, and counterpoint—are examined first by analyzing select songs from the wide body of American musical theatre literature. While tools taught in the theory sequence are used to analyze said theatre songs, jazz theory and popular music analysis also factor into our understanding of this music, allowing for an expanded treatment of common-practice theoretical methods. The repertoire selected for analysis ranges from the Tin Pan Alley musicals of the 1930s to contemporary productions, and embeds various other styles, such as jazz, pop, rock, and hip hop. Consequently, when students learn theory via musical theatre, they see concepts deployed within a wide swath of stylistic settings. In addition to viewing each topic from a strict music-theoretical viewpoint, this document emphasizes the dramatic element, allowing students and instructors to explore the relationships between music, its structure, and the on-stage drama. Each chapter, after analyzing theatre songs, will take up pedagogical considerations, posing teaching scenarios involving theatre repertoire that readers might emulate.