Study Objective: tDCS is a non-invasive (no surgical procedures are needed) procedure that delivers small amounts of electrical current to selected parts of the brain. Recent studies show that tDCS can improve verbal fluency, word recall, and perhaps even recovery of function following stroke. Although tDCS has been approved for other conditions, it has not been approved for aphasia. The purpose of this study is to determine whether tDCS will enhance the effects of speech and language therapy for people with aphasia. The study also compares two types of tDCS to determine if one of them is better and safer than the other.