classes like psychology, anthropology, and sociology, I believe. University of Chicago - Illinois requires 3 semesters in behavioral sciences, and those are the categories they supply.
aacomas did not count my one anthro class as behavioral science. i don't know if i entered it wrong, or if anthro is not considered to be the same as sociology. personally, i'd lean towards psychology if you've got to take new classes because psych is interesting and a bit more legit than sociology (imo, i know you can flame me). also, psych's going to be a big part of your practice in almost any specialty with human contact.