The promise of applied developmental science is that we can use scientific methods to promote positive human development and improve the lives of children and families. However, the present political environment in the United States makes the creation of research-informed federal policy difficult, even when the evidence supporting a given policy is unequivocal. In this essay, we hope to begin a conversation about how we, as applied developmental scientists, may modify our approach in order to best fulfill the promise of applied developmental science. To begin this conversation, we discuss the potential for establishing long-term partnerships with smaller entities, including state and municipal governments and non-governmental organizations to narrow the gap between what we know about children and families and the policies and programs that impact them. This ‘bottom-up’ approach has a long lineage in applied developmental science, and is currently enjoying a renaissance through the burgeoning interest in researcher-practitioner partnerships. Whether implicitly or explicitly, these partnerships often incorporate a systems perspective on children's development; here, we review why embracing a systems perspective may increase the likelihood of crafting policies and programs that can improve the lives of children and families. (author abstract)