Pre-exposure prophylaxis (PrEP) is an effective medicine preventing HIV transmission. This study designs and tests normative messages that promote PrEP-related information seeking among men who have sex with men (MSM) ( n = 410). Two factors were manipulated in normative messaging: type of norm (descriptive ["people do"] vs. injunctive ["people should"]) and type of pronoun (individual "you" vs. collective "we"). The results favored the use of descriptive normative appeal and collective pronouns in normative message design. For health campaigns that target MSM's PrEP-related behaviors, this study suggests that descriptive norms may increase behavioral changes whereas injunctive norms may appear intrusive and backfire. At the same time, using inclusive agency assignment (e.g., pronouns) may encourage HIV prevention through provoking solidarity considerations.