http://www.snopes.com/politics/obama/thesis.asp(This snip is part of article on the availability of her thesis)
Much scrutiny and discussion has been focused on a single phrase contained within the thesis, the statement that "blacks must join in solidarity to combat a white oppressor." This phrase has repeatedly been quoted out of context and presented as if it reflected Michelle Obama's own philosophy, but in its full context it is clearly her speculation about what she thought some of the respondents she surveyed for her thesis (i.e., students who had attended Princeton in earlier years) might have been feeling:
As discussed earlier, most respondents were attending Princeton during the 70's, at a time when the Black Power Movement was still influencing the attitudes of many Blacks.
It is possible that Black individuals either chose to or felt pressure to come together with other Blacks on campus because of the belief that Blacks must join in solidarity to combat a White oppressor. As the few blacks in a white environment it is understandable that respondents might have felt a need to look out for one another.