MS patients who meet the inclusion criteria of the study showing deficits on at least 2 of 3 attention/working measures who will then be randomized to either a treatment group (cognitive rehabilitation training) or a control group (standard clinical care). Patients must show mild to moderate-severe impairment on 2 out of 3 test measures of processing speed and sustained attention to be included in the study. Participants will undergo cognitive testing (Minimal Assessment of Cognitive Function in MS \[MACFIMS\] performed at Dr. Morrow's cognitive clinic at Parkwood Hospital) at pre- and post-treatment, and also at 6-months follow-up. Participants will also fill out non-cognitive measures in the form of questionnaires regarding quality of life (QoL), self-efficacy, stress, and copying strategies at both pre and post treatment. In addition, the intervention group will undergo attention training using CWMT for 5 days per week (30-45 minutes daily) for 5 weeks. They will complete this training by themselves in their home. The assigned Cogmed coach will set up the Cogmed program for the duration of the trail on the training group participant's computers. The study will not be able to continue to pay for the Cogmed program after the 5 week training sessions. Participants are welcome to purchase the software themselves after the entire study has ended if they would like at: http://www.cogmed.com/. The CWMT (Cogmed) method consists of 25 training sessions done online. Each participant assigned to the training group will complete eight exercises for five weeks with five sessions every week. The Cogmed program uses an adaptive training approach in which the difficulty level of the training is adjusted in real time (trial by trial basis) based on the trainee's performance. Each session consists of a selection of various tasks that target the different aspects of attention/working memory. Specifically, each session will involve training on visuospatial working memory tasks (e.g., remembering the position of objects in a 4 x 4 Grid) as well as verbal working memory tasks (e.g., remembering phonemes, letters, or digits). Given that adults will be involved in this study, Cogmed QM will be used, a version of the CWMT program adapted for adults. Participants will engage in weekly discussions over the phone for about 1 hour with an assigned Cogmed coach who will provide support and encouragement over the 5 weeks. Additional calls will be made if the Cogmed coaches see the participant is not completing their online training. Each participant will be assigned a Cogmed qualified coach who is responsible for providing structure, motivation, and feedback on training progress in order to optimize training gains. Before Cogmed training begins, each participant in the training group will be visited once by their respective Cogmed coach who will ensure that participants' daily Cogmed sessions will be conducted in a space in their home that is conducive to attention training (e.g., little clutter, private area of the home) and ensure consistency between participants. During training, each participant's performance will be tracked online and will be reviewed by the participant and his/her coach in weekly telephone meetings throughout the five week period. The participant's performance will be tracked online on the Cogmed platform. The Cogmed coaches set up the program for the participants and assign them a username. The Cogmed coaches can track the individual's performance and see who has completed the training based on their username. No Internet Protocol (IP) information will be collected. At the end of training, the coach will summarize the training by telephone with the participant.