When you apply to the program, you will be asked to list the courses you think you would like to take. Those courses will be arranged over the summer, and you will be unable to change them. Your courses for the following two terms, however, remain open. Contact the office of the Dean of the College for information. Be sure to be on the lookout for announcements about preliminary information sessions, where you'll have the chance to hear from, and ask questions of, students who have been through the program and returned to Williams for the senior year.
Competition varies greatly from year to year depending on the number of students who apply.
Admission has ranged from very competitive to not really competitive at all. However there are no set standards of admission and competition should not discourage anyone from applying to the program. Usually the rumors of admission standards are greatly exaggerated. Generally speaking, a wider array of courses is available in math and psychology than in other Division III disciplines. Almost certainly not.