On the one hand, social comparisons on social media use lead to more depressive symptoms. On the other hand, more depressive symptoms lead to more social comparison on social media. We propose an articulation of both effects. As users are primarily exposed to positive information leading to upward comparisons on Instagram and depressive individuals engage more in comparisons, they would be more vulnerable to negative impacts of comparisons on the self. Furthermore, at least two interindividual differences might explain this vicious circle, i.e. Instagram type of use and self-assessment motivation. The research tested it with correlation (N = 482), experimental (N = 185), and experimental diary design (N = 168). Two groups were asked to use Instagram actively or passively in the experimental studies. Structural equation modeling analysis showed that while the type of use didn't explain the effects, depressive symptoms, and self-assessment motivation did. Indeed, one with more depressive symptoms indicated perceives others being better off than oneself, which worsened the self-esteem (Cohen's d range for the three studies = 0.01 to 0.10), felt emotions (d = 0.03 to 0.06), and depressive mood (d = 0.02 to 0.06), and this process appears to be mediated by the motivation to self-assess.