This historical inquiry illustrates the power of social networks by examining the Starr Centre and the Whittier Centre, two civic associations that operated in Philadelphia during the early 20th century, a time when Black Americans faced numerous public health threats. Efforts to address those threats included health initiatives forged through collaborative social networks involving civic associations, health professionals, and members of Black communities. Such networks provided access to important resources and served as cornerstones of health promotion activities in many large cities. I trace the origins of these two centers, the development of their programs, their establishment of ties with Black community residents, and the relationship between strong community ties and the development of community health initiatives. Clinicians, researchers, and community health activists can draw on these historical precedents to address contemporary public health concerns by identifying community strengths, leveraging social networks, mobilizing community members, training community leaders, and building partnerships with indigenous community organizations. (Am J Public Health. 2011;Published Online Ahead of Print on June 16, 2011. doi:10.2105/AJPH.2011.300125).