It depends on your credentials while getting that BS. Honestly, a BA means little anymore. What a BA does is tell future employers that you can start and finish something....in other words, a commitment to something. After I got my BA in history, I nearly went directly after my MA in education, but decided it would be more difficult for me to find a job that way than to get a second BA in education.
I also remember that one of my professors had a Ph.D in Psychology and all of the major credentials of a psychologist but was one of the leading scholars of the Dead Sea Scrolls. He taught about the Dead Sea Scrolls as well as teaching about Judaism, Christianity, and Islam. So I guess my point here is that you can go after what you want no matter what your undergraduate degree is. I'd say you have a pretty good shot at getting into a program...but, again, it depends on how you did as an undergrad and those other grad courses.