This paper introduces application profiles as a type of metadata schema. We use application profiles as a way of making sense of the differing relationship that implementors and namespace managers have towards metadata schema, and the different ways they use and develop schema. The idea of application profiles grew out of UKOLN's work on the DESIRE project (1), and since then has proved so helpful to us in our discussions of schemas and registries that we want to throw it out for wider discussion in the run-up to the DC8 Workshop in Ottawa in October.