All students in the 31 Arts and Sciences Ph.D. programs (see Ph.D. Student Handbook, Introduction—Ph.D. Programs in section I.E.1.) must fulfill a one-year GSAS teaching requirement that must be completed in their first four years of residence (three years for students admitted with advanced standing). Students are usually appointed as teaching fellows (see Ph.D. Student Handbook, Overview of the GSAS Multi-year Fellowship Support—Fellowship Categories in section III.B.1.) while they fulfill the requirement. Students who receive GSAS multi-year fellowships must typically teach for more than a year as a condition of their fellowship support, as indicated in their official letter of admission from the dean.