The popularity of social networking sites (SNS) continues to rise globally, prompting research into the potential consequences of their usage on our well-being. Studies have produced vastly disparate findings, however, reporting positive, negative, and sometimes no associations with psychosocial outcomes. These inconsistencies may, in part, reflect a lack of consideration for how people use SNS; meaningful interactions are suggested to foster positive feelings of social connectedness, but the passive consumption of others’ feeds is proposed to promote negative feelings related to social comparison. To evaluate this claim empirically, the present study developed a novel computerised task to measure objectively styles of usage on a mock SNS platform . By administering this behavioural task online to 526 individuals, we identified three dissociable usage styles: passive use (a tendency to consume content posted by others), reactive use (a proclivity to react to [like] others’ content), and interactive use (a propensity to interact with others through content sharing). Furthermore, these usage styles differed on various subjective measures of psychosocial variables: more interactive use was associated with greater feelings of social connectedness and social capital than passive or reactive usage. Importantly, however, our data also reveal the multi-dimensional nature of usage styles, with online network size and time spent on SNS platforms serving as potentially confounding influences on some psychosocial measures. These findings advance our understanding of behaviour on SNS, and demonstrate the utility of a computerised task that can be administered under experimental conditions as an alternative to self-report and unidimensional digital tracking methods.