In general, admission into a US medical school is considered highly competitive and typically requires completion of a four-year Bachelor's degree or at least 90 credit hours from an accredited college or university. Many applicants obtain further education before medical school in the form of Master's degrees or other non science-related degrees. Admissions criteria may include overall performance in the undergraduate years and performance in a group of courses specifically required by U.S. medical schools (pre-health sciences), the score on the Medical College Admission Test (MCAT), application essays, letters of recommendation (most schools require either one letter from the undergraduate institution's premedical advising committee or a combination of letters from at least one science faculty and one non-science faculty), and interviews.