In linguistics, it has been commonly assumed that syntax can exert influence on prosody, but the opposite direction, prosody influences syntax, is much less widely recognized. The present manuscript argues for a bidirectional interaction between prosody and syntax: Syntax governs prosody and prosody also constrains syntax, based on data fromChinese. For example, a classical problem in Chinese syntax is this: only one constituent is, in general, allowed after the main verb.However, if the object is a destressed element (a pronoun, for example), two constituents can legitimately occur after the verb. This pattern is explained by proposing a prosodic feature assignment on elementary trees in the Tree Adjoining Grammar notation. The manuscript is the first work that a system of prosodically constrained syntax is proposed in the literature, and it will create a sub-field of linguistics in the study of human languages.