A neural architecture for compositional sentence structures is presented. The architecture solves the "four challenges for cognitive neuroscience" described by Jackendoff (2002). Sentence structures are encoded in this neural architecture by temporarily binding word representations with structure representations in a manner that preserves sentence structure. The architecture can store different sentence structures simultaneously. Answers to specific "who does what to whom" questions can be produced by means of a selective activation process within the architecture. The architecture can account for effects of sentence complexity.