The present article points out certain communalities between creative problem solving and Zen koan study. Both involve: 1) getting rid of prior interfering approaches; 2) satiation effects resulting from prolonged concentration; 3) a unification of contradictory events; 4) more right than left brain hemispheric functioning; 5) common psychological processes. It is proposed that both situations share the common stages of preparation, incubation, illumination, and evaluation. The stages of preparation and evaluation are seen as necessary but often overlooked aspects of the overall process. In the illumination stage, the experiences of solving a problem or a koan both have the qualities of suddeness and unexpectedness. The incubation stage involves a turning away from direct attacks on the problem, during which time realization of the solution results from the occurrence of a seemingly unrelated event.