This paper introduces MAKEBELIEVE, an interactive story generation agent that uses commonsense knowledge to generate short fictional texts from an initial seed story step supplied by the user. A subset of commonsense de-scribing causality, such as the sentence "a consequence of drinking alcohol is intoxication," is selected from the on-tology of the Open Mind Commonsense Knowledge Base. Binary causal relations are extracted from these sentences and stored as crude trans-frames. By performing fuzzy, creativity-driven inference over these frames, creative "causal chains" are produced for use in story generation. The current system has mostly local pair-wise constraints between steps in the story, though global constraints such as narrative structure are being added.