We present a constraint-based case frame lexicon architecture for bi-directional mapping between a syntactic case frame and a semantic frame. The lexicon uses a semantic sense as the basic unit and employs a multi-tiered constraint structure for the resolution of syntactic information into the appropriate senses and/or idiomatic usage. Valency changing transformations such as morphologically marked passivized or causativized forms are handled via lexical rules that manipulate case frames templates. The system has been implemented in a typed-feature system and applied to Turkish.