A number of influential linguistic analyses hold that African American English (AAE) has no verbal-s, the-s that, for example, turns drink into drinks in more mainstream English varieties.On such accounts, sentences like Mary drinks coffee are ungrammatical in AAE. Previous behavioral studies suggest that in addition to being ungrammatical, AAE speaking children find these sentences cognitively demanding, and that their presence in mathematical reasoning tests can depress scores. Until now, however, no online sentence processing study nor investigation of neurophysiological markers has been done to support these findings. Aimed at addressing this gap in the literature, the auditory ERP experiment described herein revealed two different processes associated with AAE speaking 2nd graders listening to this type of sentence: a morphosyntactic structure building problem, reflected in a bilateral early anterior-central negativity; and an increase in working memory load, indicated by a bilateral late long-lasting anterior-central negativity. Study participants also took an orally administered test of math word problems. Consistent with previous findings, results showed they answered fewer questions correctly when those questions contained verbal-s than when they did not.