To many researchers interested in connecting their research to policy decisions and advocating for increased federal investment in science, the federal policy-making and appropriations processes may feel distant and difficult to navigate. The goal of this article is to provide an overview of the federal budget and legislative processes, as well as an understanding of the congressional offices and committees managing these processes, with information about how policymakers incorporate evidence into their work and the challenges they face. The article describes the policy-making ecosystem, in particular the role of the advocacy community. We identify specific points in the process that provide opportunities for researchers and advocates to weigh in on important issues such as federal funding for science and the scientific workforce. Case studies are provided demonstrating two advocacy successes. Finally, we provide a list of relevant resources.