The leitmotif of this study is economy, both at the linguistic and the analytic level. It explores the following subjects: definite articles in Bulgarian, Romanian, and Albanian and their suffix features; noun markings in combinations with attributes (e.g. in Persian) as an expression of semantic transparency; the role of economy in agreement morphology and its theoretical significance. By integrating the structural levels of semantics, morphology, syntax, and phonology, this approach is able to explain numerous apparently problematic features as representing interface phenomena.