Partnerships have taken on added importance in recent years because of their critical role in addressing complex public health problems and translating evidence-based practices to real-world settings. The Merck Childhood Asthma Network, Inc. initiative recognized the importance of partnerships in achieving the program's goals. In this article, case studies of the five Merck Childhood Asthma Network program sites describe the role of partnerships in the development and evolution of the program and its interventions. Three key factors contributed to the success of the partnerships: having common organizational goals, considering context in the selection and engagement of partners, and ensuring that each partnership benefited from the alliance. Over the 4-year program period, all five partnerships evolved, matured, and had an established goal to maintain collaboration.