<p>Theoretically, if I wanted to enroll in say a mathematics PhD program, would I need a bachelor's degree in mathematics? Or is graduate school more like medical school in saying "You can major in whatever you want, you just have to take these required courses?"</p>
<p>I can’t speak for a mathematics Ph.D., but Ph.D. programs in the humanities (English, history, etc.) won’t require that you major in the field, but they want to make sure that you have significant undergraduate work in the field.</p>
<p>I would say, generally you need an undergrad degree in a similar field in order to get accepted into a grad program. So, if you had an undergrad degree in Physics, for example, you might be accepted into a Math grad program. On the other hand, if you have an English Literature degree, they aren’t even going to look at your application.</p>
<p>what about unrelated field + math minor -> math PhD program?</p>
<p>or semi related field such as chemistry + math minor -> math PhD program?</p>
<p>From the UCLA math dept website:
The Mathematics major is designed for students who are interested in the theory of mathematics. Pure Mathematicians often pursue Master’s degree and Ph.D’s in Mathematics in order to prepare for a career in research or university level teaching.</p>
<p>In science there is not a hard fast rule at most places, but in practice you will need a bachelors in the same or related field. How closely they must be related probably varies a bit by department. I have a Ph.D. in Immunolgy, specifically cellular immunology, but my B.S. was in Zoology - different fields but with a lot of overlap in biology and chemistry course work. </p>
<p>To get into a Ph.D. program in Math with B.A. in say Dance would probably be tough. But a B.S. in Physics or Statistics with a high score on the Math GRE might do.</p>
<p>The “required courses” you speak of would probably be, if you wanted pure mathematics: Real Analysis, Abstract Algebra and Linear Algebra at a minimum (preferably some experience with Complex Analysis and Topology, too). A math minor just doesn’t cut it.</p>
<p>But if you wanted to do computational mathematics or discrete mathematics or statistics or operations research, then the courses look different that they’ll look for. Also, if you do something interdisciplinary - mathematics modeling in political science, biology or chemistry or something with computer science/mathematics, then maybe there’s justification for having your PhD differ from your undergrad major.</p>
<p>Also, top math programs will like to see that you’re capable of doing research i.e. a Senior thesis, an REU and/or directed research with a prof.</p>