Body condition at the time of calving is the most important factor affecting rebreeding performance of normally managed beef cows. Body condition changes before and after calving will have more subtle effects on rebreeding especially in cows that are in marginal body condition. Body condition changes from the time the cow calves until she begins the breeding season can also play a significant role in the rebreeding success story. This appears to be most important to those cows that calve in the marginal condition score range of "4" or "5". An Oklahoma trial illustrates the vulnerability of cows that calve in the body condition score of 5. Two groups of cows began the winter feeding period in similar body condition and calved in very similar body condition. However, after calving and before the breeding season began, one group was allowed to lose almost one condition score (from 5.3 to 4.6). The other group of cows was fed adequately to maintain the body condition that they had prior to calving. The difference in rebreeding rate was significant (73% vs 94%). Again this illustrates that cows that calve in the body condition score of 5 are very vulnerable to weather and suckling intensity stresses and ranchers must use good nutritional strategies after calving to avoid disastrous rebreeding performance.