During the last century, increasing milk production has been associated with decreasing reproductive performance. However during the last decade, there has been a dramatic improvement in reproduction even as milk production continues to increase. The reasons for improving reproduction are multifactorial with dramatic improvements in reproductive management programs, advances in cow comfort and health management programs, and a turn-around in the genetics of reproduction underlying some of these gains. In addition, older research and many recent studies indicate that gains in reproductive performance require optimized nutritional programs including 4 specific areas that will be emphasized in this presentation. First, nutritional deficiencies in the prepartum diet can affect reproduction. As an example, recent research indicates that supplementation during the last month before calving with vitamin E in marginally-vitamin E deficient dairy cattle decreased retained placenta and stillbirths and increased subsequent reproductive performance. Second, nutritional deficiencies near calving and during the first 21 d after calving can have substantial effect on subsequent reproduction. In a recent retrospective study and consistent with previous results, we observed changes in BCS during the first 21 d after calving were associated with dramatic differences in fertility in high-producing lactating dairy cows. Third, increased insulin during the week before AI, potentially due to diets with high non-fiber carbohydrates, can have negative effects on fertilization and reproductive performance of ruminants. Thus, reducing insulin by targeted but subtle changes in feed intake or energy composition of the diet could be used to improve reproduction. Fourth, optimization of amino acid composition of diets may improve reproductive efficiency. Our recent research demonstrates that supplementing rumen-protected methionine altered gene expression in early preimplantation embryos and reduced subsequent pregnancy loss in lactating dairy cows. Thus, inadequate nutritional programs can reduce reproductive performance and optimized nutrition may augment reproduction even in herds with enhanced genetics and reproductive management strategies.