We assessed individual and collective responses to HIV pre-exposure prophylaxis ('PrEP') among a network of male sex workers and clients. From 2011 to May 2017, keyword searches on an online discussion forum identified 668 posts that referenced PrEP. We conducted four analyses: (i) discourse analysis identifying reactions to PrEP, (ii) thematic analysis constructing rhetorical strategies, (iii) content analysis comparing discursive positions and rhetorical strategies, and (iv) longitudinal analyses assessing trends over time. Forum posts adopted one of three discursive positions (reluctance, interest, advocacy), drawing upon four non-exclusive strategies (deference to experts and evidence, acknowledging personal and shared experiences, establishing philosophical arguments, engaging in speculation). Posts from sex workers were more likely than clients to be supportive of PrEP (96% vs. 42%; χ2 = 18.46, p < 0.001) while over time this network moved from being predominantly reluctant about PrEP (61% of posts in 2012) to advocating for its use (65% of posts in 2017; Z = 5.01, p < 0.001).