A key challenge in the representation of qualitative, multi-criteria preferences is to find a compact and expressive representation. Various frameworks have been introduced, each of which with its own distinguishing features. In this paper we introduce a new representation framework called qualitative preference systems (QPS), which combines priority, cardinality and conditional preferences. Moreover, the framework incorporates knowledge that serves two purposes: to impose (hard) constraints, but also to define new (abstract) concepts. In short, QPS offers a rich and practical representation for qualitative, multi-criteria preferences.