Contrast plays an important role in accounting for the patterning of vowel systems in the Manchu languages. The phonological representation of a vowel depends in part on what other vowels it contrasts with. We will show that although Written Manchu /i/ phonetically has advanced tongue root (ATR), it is not contrastively ATR, and hence does not trigger ATR harmony. Similarly, Written Manchu /u/ is phonetically, but not contrastively, labial. We will also argue for a particular way of determining contrastiveness, in terms of a contrastive hierarchy of features. Our analysis of the Written Manchu contrastive hierarchy is further supported by synchronic and diachronic evidence from Spoken Manchu and Xibe.