Abstract This article puts forward two ways of understanding capacity: strong and weak theories. The strong theory of capacity self-evidently connects capacity with ideal humanity or pedestalizes it as an analytic concept, while the weak theory of capacity allows space for interpretations about life unfolding without murmurings about capacity. By considering capacity in a way that distinguishes these two theories, the article contributes to contemporary thinking in which capacity has emerged as a key concept. My perspective draws on Eve Kosofsky Sedgwick’s ideas about strong and weak theories and is further influenced by methodological issues raised by disability studies scholars. I first recall Sedgwick’s ideas about strong theories, after which I focus on how capacity assumptions operate in Silvan Tomkins’ work, which has had an important impact on Sedgwick. I then identify two recent contributions in disability studies in the area of capacity-themed theorizing. I interrogate the ways in which these contributions share the habits of the strong theory and how they escape its problematic tendencies. Toward the end of the article, I outline how the weak theory of capacity could contribute new perspectives to the contemporary discussion.