Mental health disclosures increasingly occur on online platforms. In a moderatedmediation analysis, we assessed an adapted Corrigan's attribution model (2003) including factors such as the sincerity of online disclosure and support self-efficacy to predict helping intentions on social media. Participants (N = 177) were randomly allocated to one of three conditions and presented with a social media vignette experimentally manipulating controllability attributions (low, high, neutral controllability). Participants completed controllability, sincerity, sympathy, self-efficacy, and helping intentions questionnaires. While preliminary exploratory analyses revealed that the proposed model significantly explained helping intentions, the proposed mechanisms of serial-mediation via sincerity of disclosure and sympathy was not supported, nor was this dependent on self-efficacy. Nonetheless, sympathy and selfefficacy uniquely and significantly explained helping intentions. Thus, an intervention that upskills individuals in online support provision offers promise in terms of accessible, online, community-based treatment initiatives.