This chapter sets the context for the new text-task-respondent (TTR) theory of functional literacy, beginning with a brief history of the conceptual underpinnings of the U.S. national assessments of adult literacy as task-based assessments. Then it lays out the rationale for reconceptualizing functional literacy in light of traditional views of literacy and changing literacy demands-and presents the case for a theory that integrates task-and skill-based dimensions. The chapter concludes with a brief overview of the new theory’s practical implications.