Recent developments in Korean archaeology, especially the discovery of well-preserved rice grains in clear archaeological contexts, have caused a reassessment of the timing, distribution, causes, and effects of the beginning of rice agriculture in Korea. Kim puts the rice discoveries in historical perspective, discusses details of the recent evidence, and explores possible diffusion routes based on the new data. Choe focuses on semi-lunar knives—the agricultural tools believed to be associated with rice cultivation. The typology of the knives and the distribution and chronology of the types are used to propose a diffusion route directly into Korea from North China. Nelson examines the cultural changes from the preceding Chŭlmun period when rice grains and semi-lunar knives are found. Mechanisms to explain the change are proposed as hypotheses. Comments on the papers disclose an agreement on the likelihood of a northern diffusion route, but no consensus on the cultural processes.