While many have strongly suggested that transcranial direct current stimulation (tDCS) may represent a beneficial intervention for patients with primary progressive aphasia (PPA), this promising technology has not yet been applied widely in clinical settings. This treatment gap is underscored by the absence of any neurally-focused standard-of-care treatments to mitigate the devastating impact of aphasia on patients' family, work, and social lives. Given that tDCS is inexpensive, easy to use (it is potentially amenable to home use by patients and caregivers), minimally invasive, and safe there is great promise to advance this intervention toward clinical use. The principal reason that tDCS has not found wide clinical application yet is that its efficacy has not been tested in large, multi-center, clinical trials. In this study, scientists in the three sites that have conducted tDCS clinical trials in North America-Johns Hopkins University and the University of Pennsylvania in the US, and the University of Toronto in Canada, will collaborate to conduct a multi-site, Phase II clinical trial of tDCS a population in dire need of better treatments.