Sociocultural perspectives on literacy include various theories focused on the myriad ways in which people use literacy in context, which include a strong emphasis on power relations. Yet, these theories also have important differences, and many in the field of literacy do not clearly differentiate among them. I provide a critical overview of influential sociocultural perspectives on literacy, focusing on three major perspectives: (1) literacy as social practice, (2) multiliteracies, and (3) critical literacy. In an effort to support researchers in framing their scholarly work and to support practitioners and other consumers of research make sense of research, I discuss the ways in which each theory would answer the question, "What is literacy?" as well as the affordances and limitations of these theories in terms of literacy development, literacy use, and literacy instruction. (Contains 2 figures.)