This study tests whether aphasia or alexia, language and reading disorders occurring after traumatic brain injury or stroke, can be improved using transcranial direct current stimulation (tDCS). tDCS is a non-invasive technique that applies a small amount of direct electrical current to the brain in order to temporarily alter brain processing. Adults with aphasia/alexia resulting from stroke or traumatic brain injury will undergo baseline behavioral testing of various language and cognitive functions. Subjects who are willing to undergo MRI evaluation will also be scanned. They will then receive five days of either real or sham tDCS with standardized speech-language therapy, under a double-blind randomized placebo-controlled design. Behavioral assessments, and MRIs for those participating in the MRI portion of the study, will be performed again at multiple time points after completing tDCS to assess for changes in these measures.