Abstract. In the current study we examined a psychological mechanism linking Facebook use to depression. A survey was conducted with 319 undergraduates about their passive Facebook use, their frequency of making upward social comparisons on Facebook, the emotions evoked through these comparisons, and their levels of depression. Half of the participants were given questions about the Facebook comparisons they made with their close friends, while the other half were given questions about the Facebook comparisons they made with acquaintances. Analysis of the whole sample revealed that upward Facebook comparison elicited assimilative emotions (inspiration, optimism, and admiration) more than contrastive emotions did (envy and resentment). A path model was developed in which passive use of Facebook predicted the frequency of making upward social comparisons, and, in turn, the frequency of making upward Facebook comparisons predicted depression through two routes: one through contrastive emotions and other through assimilative emotions. The results suggested that the model fits the data. As expected, the frequency of upward Facebook comparisons was associated with the increases in frequency of both contrastive and assimilative emotions, and the associations of these two types of emotions with depression were in opposite directions: Depression increased as the frequency of contrastive emotions increased, and it decreased as the frequency of assimilative emotions increased. The strength of the latter aforementioned association was stronger when the comparison targets were acquaintances rather than close friends.