The Internet widely display interactions between various parties, calling for research to understand how message- and source-related factors in these easily observed interactions influence observers' attitudes in health contexts. From a masspersonal communication perspective, we investigated how reading a conversation about seeking counseling between two members of an online support group affects individuals' attitudes toward counseling-seeking behavior. In the conversation, one group member asked for advice about depressive symptoms, and in our online experiment with adults living in the United States (N = 250), we manipulated the responding source's expert status and framing of the message that recommended seeking counseling. Guided by an overarching theoretical framework-dual-process theory of supportive communication outcomes, we found a significant three-way interaction among severity of depressive symptomatology (low vs. high), message framing (gain vs. loss), and source expertise (peer vs. peer counselor vs. professional counselor). When a peer counselor provided the message, loss framing reduced self-stigma toward seeking counseling to a greater degree than gain framing and, in turn, induced more favorable attitudes toward the behavior among people with a high severity of depressive symptomatology. Those findings provide theoretical insights into the masspersonal communication approach to health promotion and inform promising communication strategies to promote counseling-seeking behavior among people with depressive symptomatology.