Although attitudes are frequently hypothesized to guide information system (IS) usage behavior, existent empirical evidence on their explanatory power is inconclusive. We thus suggest in this paper the consideration of an attitude's strength that stems from its structural consistency. First, we illuminate the structure that underlies attitudes from a theoretical perspective and hypothesize that its consistency marks strong attitudes that explain IS usage. Second, we provide empirical evidence on structurally consistent attitudes explaining IS usage intention in the specific context of social network sites. By focusing on attitude, we investigate in this paper a less-studied side of existent IS adoption theories and show the merits of considering an attitude's strength as indicated by its structural consistency in explaining IS usage.