Only 7% patients can walk safely in the community. Functional community ambulation requires the ability of walking while performing other tasks. It is emergent to establish dual-task walking assessment with good psychometric properties and to identify the most effective approach that enhances dual-task walking performance for stroke patients. Our ongoing study found that motor tasks combined with cognitive dual-task training (multi-tasking ) have more improvements on cognitive performance of the Stroop task while walking than cognitive dual-task training alone. Therefore, combined motor and cognitive elements to walking training might be considered as a novel therapeutic strategy to promote functional ambulation and recovery of stroke patients. This combined strategy is based on attentional capacity sharing theory and the research advances on dual-task to enhance active participation and cognitive involvement, strengthen dual-task walking ability, then transfer to promote community ambulation and participation. However, lacking prospective, controlled trials quantify gait and cognition under dual-task conditions after multi-task walking training. Specifically, we will investigate psychometric properties of dual-task walking assessments for chronic stroke individuals. The second aim is to compare the immediate, retained, and transfer effects of of multi-task overground walking training to multi-task treadmill walking and traditional rehabilitation on walking function, cognitive performance, task coordination, and community ambulation in patients with chronic stroke. A metric analysis and comparative efficacy research will be conducted. Sixty chronic stroke patients will receive dual-task walking assessments twice at pretreatment with a 1-week interval for test-retest assessment and investigation of the reliability and validity of outcome measures. The primary outcome measure of the dual-task walking assessments will include walking at preferred speed and fast speed and simultaneously perform the Stroop task. Concurrent validity will be studied to validate the dual-task walking measures with each other and with the item 14 of the mini-Balance Evaluation Systems test (Mini-BESTest), dual-task Timed-up-and-Go test (dual-TUG), and 6-min walk test obtain concurrently for assessing dual-task ability. In addition, we will compare dual-task walking performance between fallers and non-fallers to examine discriminant validity of dual-task walking assessments. A comparative efficacy research is a single-blind, randomized controlled trial, which will be conducted at medical centers. Sixty ambulatory stroke patients will be randomized to multi-task overground walking training or multi-task treadmill walking training or traditional rehabilitation. All three groups will receive interventions 3 times a week for 4 weeks. The multi-task overground walking training group will undertake overground walking training while concurrently perform motor and cognitive tasks. The multi-task treadmill walking training group will train the same set of motor and cognitive tasks while walking on the treadmill. Traditional rehabilitation will train strength, balance, and gait. A blinded assessor will administer three assessments All participants will be examined gait and cognitive performance under single-task (walking only, cognitive tasks only) and dual-task conditions (walking while performing the Stroop task) at baseline, post intervention, and 1-month follow-up. The primary outcome measure of gait and cognition is gait speed and composite score of accuracy and reaction time of the cognitive tasks under single- and dual-task conditions. The secondary outcome measures will be the Mini-BESTest, single- and dual-TUG, Functional Gait Assessment, 6-minute Walk Test, physical activity monitor, and Stroke Impact Scale. Repeated measure ANOVA will be used to compare measurements at baseline, after training, and follow-up among the groups.