Despite its appeal and widespread use, the term scaffolding has been inconsistently invoked across the field of education, particularly in literacy research. Indeed, its meaning has become so broad that its impact on learning is unclear. This review elucidates the theoretical tenets that underpin the metaphor and critically examines the impact of scaffolding on literacy learning by interrogating the existing literature in terms of its adherence to the theoretical tenets of the construct and the methodology used to determine the relationship between teachers' scaffolding and students' literacy learning. Guidelines for future research are offered to advance understanding of the role of scaffolding in literacy learning. In offering these guidelines, we endeavor to adhere to the theoretical underpinnings of the concept and address methodological weaknesses in extant empirical research.