Research in the teaching and learning of undergraduate quantum mechanics is being conducted at the University of Washington [1] and Grand Valley State University [2]. Because of its central role in quantum mechanics, we are investigating how students come to learn about probability. Our research has included the analysis of individual demonstration interviews, ungraded quizzes, and course examinations. We will show evidence that many students inappropriately use their intuition about classical mechanics in order to predict or account for quantum mechanical phenomena.