The tendency to disclose personal information on Facebook has been examined in relation to the broad Big Five personality factors (extraversion, openness, neuroticism, conscientiousness, agreeableness), but the potential roles of more specific traits such as alexithymia and impulsivity are not known. The present study assessed the ability of these two traits, along with indices of disordered social media use, alcohol use, negative mood, and demographic factors, to predict Facebook self-disclosure in a hierarchical regression model. The study recruited 157 Facebook-using adults aged between 18 and 30 years (M = 24.31 years), of whom 81 (51.6%) identified as female, from across Australia via the online survey tool Qualtrics. Expected significant positive correlations of Facebook self-disclosure with alexithymia, impulsivity, disordered social media use, negative mood and alcohol use were obtained. In the final regression model, alexithymia and anxiety were the strongest predictors, followed by alcohol and education; disordered social media use, impulsivity, depression, stress, age, and gender were not significant. Subsequent analysis revealed that of the three facets of alexithymia, only difficulty identifying feelings explained variance in Facebook self-disclosure. Findings are interpreted in terms of the social compensation hypothesis and recent neuroimaging evidence of blunted brain response to social rejection in alexithymia.