In 2016, the EveryLife Foundation for Rare Diseases, in partnership with Dr Pan, who is a pediatrician and state senator in California, launched legislation to advance and expand newborn screening. Researchers have shown that newborn screening can be cost-effective and can greatly improve health outcomes for patients with rare diseases. However, adding additional diseases in newborn screening is a long process, requiring legislative approval in addition to new state funding. Such process delays can lead to protracted diagnostic odysseys for patients, especially those with rare diseases. These delays can result in irreversible morbidity and, in some cases, early mortality for patients. To improve this process, legislation known as Senate Bill 1095 was introduced to require California to adhere to the latest federal recommendations for newborn screening within 2 years. We provide insight and describe the process of advancing state legislation, coalition building, and managing opposition. Senate Bill 1095 would become law in 2016, requiring California to screen for 2 new rare diseases by August 2018: mucopolysaccharidosis type I and Pompe disease. This case study can serve as a model for advocates looking to expand state newborn-screening programs.