IB History of the Americas is generally taken by students who have already taken a year of U.S. History prior to the IB Diploma programme. It encompasses North American and South American study for both SL and HL Candidates. Both SL and HL students are required to complete one Historical Investigation to be turned in to the IBO before they take their test. HL Candidates delve further into History by looking at one Single-Party State, usually chosen by the instructor.