This paper documents the artistic construction and spectatorial reception of a student production of Paul Zindel’s "The Effect of Gamma Rays on Man-in-the-Moon Marigolds" at the University of Pennsylvania. The performance, which allowed audience members to make suggestions that could subtly or radically alter the trajectory of the play at any point during the performance, provides empirical data concerning the actor-audience co-production of theatrical meaning. The paper focuses on three aspects of this theatrical dialogue: the behavior of the student audience at the performance, the audience’s “spectatorial literacy” and the concomitant disparity between intended and actual meaning, and the actors’ ability to stay in character under audience-modifiable action. Finally, an analysis of the actor-audience interactions leads the author to propose a new ideational framework for the study of theatre, its nature and role in society