This paper reviews evidence concerning the nature of grouping in music and language and their interactions with other linguistic and musical systems. I present brief typological surveys of the relationship between constituency and acoustic parameters in language and music, drawing from a wide variety of languages and musical genres. The two domains both involve correspondence between auditory discontinuities and group boundaries, reflecting the Gestalt principles of proximity and similarity, as well as a nested, hierarchical organization of constituents. Typically, computational-level theories (...) of musical grouping take the form of a function from acoustic properties through grouping representations to syntactic or interpretive constituents. Linguistic theories tend to be cast as functions in the opposite direction. This study argues that the difference in orientation is not grounded in principled differences in information flow between the two domains, and that reconceptualizing one or both theories allows for gains in analytical understanding. There are also obvious differences between musical and linguistic grouping. Grappling with those differences requires one to think in detail about modularity, information flow, levels of description, and the functional nature of cognitive domains. (shrink)