The relationship between music and Tang poetry is a topic of ongoing interest, usually approached from the perspective of individual genres. This article considers the relationships of three major genres of Tang poetry to music, morality, and one another to argue that musical and ethical considerations were important factors in the waxing and waning of those genres. By the mid-Tang, and perhaps much earlier, the musical system for Han and Six Dynasties yuefu poetry had been lost. Citing poems, critical writings, and histories of such poets as Shen Yue, Yuan Jie, Bai Juyi, Yuan Zhen, and Li Qingzhao, however, this article shows how yuefu, shi, and quzi ci poets reappropriated the idea of "music bureau" pieces to experiment with, and stand in for, even older, Confucian ideals on the relationship of lyrics to music and morality. By citing examples where ethical considerations prompted poets and musicians to reinvent and reinterpret older forms, this article complicates the notion of a straight line of development from folk song to literati imitation to antiquarian exercise.