A crop rotation study was begun in 2000 at Bozeman, MT, to study the role of crop diversity to reduce traditional crop inputs within No-till and Organic cropping systems. The goal was to seek synergistic knowledge about reducing herbicide inputs in No-till systems and reducing tillage in Organic systems. Systems response changed during two cycles of 4-yr crop rotations. In Cycle I, winter wheat grown in the Organic cropping system yielded equal or greater than winter wheat grown in three No-till scenarios, leading to favorable economic comparisons despite a 3-yr market transition period. However, in Cycle II, winter wheat crops failed due to climatic or disease constraints, highlighting the risk associated with forgoing pesticide use. Due to mild wet winter weather, and sudden onset of summer drought, it was hypothesized that winter growth habits would provide crops a significant yield advantage. During drier than normal years (i.e. 330 to 355 mm annual precipitation) winter and spring wheat yields were equal. However, in a normal precipitation year in 2006 (418 mm), winter wheat outyielded spring wheat by 45%. We also hypothesized that winter wheat in the most highly diverse No-till system would yield the greatest because of optimal pest management. Winter wheat yields were lowest in this highly diversified cropping system from 2000 to 2004, due mainly to yield depression two years after sunflower. The crop rotation was altered to place sunflower 3 yr before sunflower, and winter wheat yield in 2006 was greatest in this rotation. These are but some of the lessons in this cropping systems study that appear to be changing with time. How long should I plan to run this study?