AbstractWhat does it take to run a full substance-free phonology (SFP)? Because in classical approaches only items below the skeleton have phonetic properties that, according to SFP, need to be expunged, current work in SFP only ever concerns segmental aspects. If substance is removed from segmental representation and primes and computation are therefore arbitrary, the non-trivial question arises: how can such a system communicate with a system where primes and computation are not arbitrary (at and above the skeleton)? The two phonologies below and at / above the skeleton that exist in production are complemented with a third phonology that occurs upon lexicalization, that is, when L1 learners or adults transform the acoustic signal into a stored representation. The core of this article argues that this broad architecture is inhabited by three distinct computational systems along the classical feature geometric divisions: Son(ority) is located at and above the skeleton, while Place and Lar(yngeal) live below the skeleton. The question then is how a multiple-module spell-out works, that is, how ingredients from three distinct vocabularies can be mapped onto a single phonetic item. It is argued that the skeleton plays a central role in this conversion.