In this chapter, we examine different views of the structure of justification, including foundationalism, infinitism, and coherentism. We investigate how well or poorly they seem to do in responding to the regress problem, accommodating a robust connection between justification and truth, and getting the contours of justification right—i.e., making justification neither too easy nor too hard to get. We end by briefly discussing some challenges to finding a single sense of “foundational belief” defining the debate.