English proficiency is required for all courses except those offered by the Institute for English Language Programs. See the English proficiency requirement.
Required placement tests are listed in course descriptions.
Some course descriptions also list recommended prerequisites. Although you do not have to prove that you have met these, you are responsible for ensuring you are adequately prepared for your course.
If you have questions about prerequisites other than English proficiency or placement tests, contact the instructor after registration begins. Contact information is generally listed on syllabi, linked in course descriptions. Some instructors are also listed in the Harvard directory.
In some courses, instructors give assignments during the first class to confirm that you have met prerequisites. Based on the results or on your general performance, you may be dropped during the course change period and required to move into courses that are more appropriate for your skill level, prior education, or English proficiency.
See Student Responsibilities for more information.