This chapter examines the phenomenon offocus projection: a sentence with prosodic marking of focus on a word can lead to ambiguity, in that different constituents containing the word can be interpreted as focused. Two general approaches to focus projection are compared. In Default Prosody analyses, focus projection is epiphenomenal, a consequence of general principles requiring that focus be prosodically prominent, coupled with default principles of default prominence. In the F-projection approach, focus projection is encoded more directly, in terms of licensing rules for F-marking on constituents. Overall, the evidence in the literature favors the Default Prosody approach, and this chapter concentrates on comparing these two general approaches, as well as briefly summarizing other aspects of focus projection. The chapter ends with discussion of Basque data that are problematic for widely assumed generalizations about focus projection, and a possible way of understanding the data in the Default Prosody approach.