OBJECTIVES/SPECIFIC AIMS: The goal of this study is to measure speech fluency and brain activity before and after 5 days of behavioral speech fluency training alone (sham group) or speech training plus stimulation (active group). A 1-month follow up will also be completed. The first primary outcome measure is changes in brain activation in speech motor control/timing network. The second primary outcome measure is changes in percentage of stuttered syllables during speech sample (speech fluency). The secondary outcome measure is changes from baseline on the Overall Assessment of Speakers Experience of Stuttering (OASES), a detailed subject rating of how stuttering affects their lives. METHODS/STUDY POPULATION: This study is a between subjects, counterbalanced, sham-controlled, double-blind design. Participants will be 40 adults who stutter who will be randomized (using minimization) into either the active or sham stimulation group, with all other study procedures being the same in both groups. Participants will completed 2 days of baseline testing, 5 consecutive days of brain stimulation during speech training, 2 days of post-testing, and a 1-month follow up. All outcome measures will be completed immediately before and after the 5 days of brain stimulation, as well as at follow-up. as of submission, 10 subjects have completed the study. Data collection is ongoing. RESULTS/ANTICIPATED RESULTS: Expected results. Questions this study aims to answer: 1) Does a more intensive training period lead to decreased stuttering? We expect that both groups will show improvements in speech fluency immediately after training. We expect that those in the active group will continue to exhibit improved speech fluency at 1 month follow up. 2) Does a more intensive training period lead to changes in brain activity? We expect that both groups will exhibit increased activity in auditory/motor regions immediately after training. We expect that the active group will continue to exhibit an increase in activity in these regions at 1 month follow up. DISCUSSION/SIGNIFICANCE OF IMPACT: This is the first RCT study involving brain stimulation in adults who stutter. We expect to provide preliminary evidence for the effectiveness of tDCS as an augmentative agent for increased speech fluency in adults who stutter during a brief, intensive training paradigm. We also expect to be able to provide information on the effects of tDCS on brain activity in speech and auditory-motor regions of the brain. The findings will add to the growing body of literature suggesting that developmental stuttering is a neurodevelopmental disorder with roots in timing and rhythmic aspects of speech motor control and auditory-motor integration.