The paper develops a constraint-based theory of prosodic phrasing and prominence, based on an HPSG framework, with an implementation in ALE. Prominence and juncture are represented by n-ary branching metrical trees. The general aim is to define prosodic structures recursively, in parallel with the definition of syntactic structures. We address a number of prima facie problems arising from the discrepancy between syntactic and prosodic structure