Evidence indicates that health information seekers employ various sources—like health care providers, print media, and online support groups—in the information acquisition process. Two studies examine the role of information sources in the health information-seeking process and test Ruppel and Rains’s (2012) extension of channel complementarity theory. Four complementarity features of sources, which are claimed to function as a basis for source use during information seeking, were explored: access to medical expertise, tailorability, anonymity, and convenience. Taken together, the findings from both studies provide some evidence that sources are employed systematically during health information seeking based on each of the four complementarity features.