A graduate school is a school that awards advanced academic degrees (i.e. master's degrees and Ph.D. degrees) with the general requirement that students must have earned a previous undergraduate (bachelor's) degree. A distinction is typically made between graduate schools (where courses of study do not provide training for a particular profession) and professional schools, which offer specialized advanced degrees in professional fields such as medicine, business, ministry or law.

Many universities award graduate degrees; a graduate school is not necessarily a separate institution. While the term "graduate school" is typical in the United States and often used elsewhere (e.g., the UK and Canada), "postgraduate education" is also used in some English-speaking countries (Australia, Canada, India, New Zealand, and the UK) to refer to the spectrum of education beyond a bachelor's degree. Those attending graduate schools are called "graduate students" (in both American and British English), or often in British English as "postgraduate students" and, colloquially, "postgraduates" and "postgrads". Degrees awarded to graduate students include master's degrees, doctoral degrees, and other postgraduate qualifications such as graduate certificates and professional degrees.