MIT PRIMES (Program for Research in Mathematics, Engineering and Science) is a free, year-long after-school research program for high school students. Program participants work with MIT researchers on exciting unsolved problems in mathematics, computer science, and computational biology. PRIMES-USA is a distance mentoring math research section for high school juniors from across the United States (outside of Greater Boston). PRIMES Circle is a math enrichment section for high school students from underrepresented groups living within commuting distance from Boston. PRIMES STEP is a math enrichment section for middle school students from Greater Boston.