The first option is acquiring some hard skills. Engineering, nursing, IT, and teaching or training are good examples. An appropriate terminal degree, combined with a minor in a foreign language (not French or Spanish unless you can become fluent. Turkish and Urdu are good choices for poor language learners as they are a little easier to learn and yet are exotic enough that no one expects fluency. If you’re good with languages, go with one of the major difficult ones – Russian, Arabic, or Mandarin Chinese) or international relations will open a lot of doors.
The second option is to study international development and/or its related disciplines. This will require a graduate degree and it covers a lot of different study options; I’d include international or public health, public policy, conflict studies, “development studies” and the big one, development economics. The trick to this path is that it can be very hard to go abroad with these kinds of degrees, because you’re not really doing anything a development project needs in the field. You run the risk of getting tracked into headquarters-based jobs – academia or think tank if you’re lucky, program backstopping if you’re not so lucky. The best way to mitigate that risk is to acquire whatever hard skills you can (grantwriting is a good one) while in school, and intern as much as humanly possible. Abroad if you can, of course.
Anyone want to talk about their own study and where it led them?
ETA: Ethan Zuckerman commented below and mentioned a big thing I left off – time overseas. If you want a job in the developing world, people will feel a whole lot better if they already know you can hack living there. I talk about this in my Damsels in Success post a bit. One useful thing to say here: STUDY ABROAD. It’s the easiest way to fully immerse yourself in another culture. And choose somewhere tough. Auckland or Paris does not count. I did my own study abroad in Cairo, and I know that employers saw that as clear evidence that I could adapt easily in other places. (And they’re right – if you can live in downtown Cairo, you can live almost anywhere.)