Certified organic crop production is the fastest growing segment of agriculture in the United States today, increasing at a rate of more than 20 percent annually.  The transition from conventional farming practices to organic is complicated, yet, growers interested in organic farming have very limited resources in the scientific literature to turn to for guidance in making the transition.  This study focuses on the agronomic (weed management, yield, soil fertility, quality and sustainability) dynamics during the critical three-year transition phase from conventional farming to certified organic.  The research will result in the development of best management practices for growers to follow in transitioning to a certified organic system in corn, soybean, wheat and alfalfa.  Two different organic cropping systems are compared here:  A four-year organic rotation of corn, soybean, wheat and alfalfa which incorporates dairy manure and cover crops vs. one year of conventional corn followed by three years of continuous organic alfalfa without manure or cover crops.  Results indicate yields exceeding local and regional averages during the first transitional (corn) year with no significant difference in yield between the two treatments during the first and the final (certified) corn rotation.  Economic analyses after the final year in the field have determined the most cost effective method of transitional management to be that of the more complex four-year rotation.