Resistance to intramammary infection requires recognition of the invading organism, recruitment and activation of immune defenses, elimination of the organism, and return to homeostasis. The effectiveness of this response reflects a complex series of interactions among the cow’s immune system, her environment, and mastitis causing organisms. As such, the genetic contribution or heritability of mastitis is relatively low when compared with these other factors and genetic progress will be slow. To improve the rate of genetic change, gains must be made relative to reliability, selection intensity, and/or heritability of the trait itself or highly correlated traits. With changes in the industry and technology, we have newfound opportunities to increase the speed and accuracy of genetic gains for mastitis resistance. The keys to this opportunity reflect greater use of producer recorded data to improve reliability of genetic predictions, creation of novel phenotypes from currently recorded data such as SCC to improve reliability, selection intensity and/or heritability, as well as creation of novel measures of the immune system. These changes are coupled with another significant event in the industry, sequencing of the bovine genome, which has enabled the association of individual differences in DNA sequence with traits of interest – e.g., genomics. This has reduced the generation interval and thereby the rate of genetic change by identifying superior sires at younger ages, without the need for daughters to complete their first lactation. Furthermore, a DNA sequence is more “heritable” when compared with a phenotype which is influence by genetic and environmental factors. As we continue to progress, genomic evaluation of current and novel phenotypes will increase the speed and accuracy of selecting for mastitis resistance. Perhaps just as important, genomic markers can provide model systems to better understand the mechanisms that lead to mastitis resistance and enable a more targeted approach to new strategies against mastitis. This symposia will summarize recent advances in relation to historical practices.