This is a case series study evaluating the feasibility and dosage of Intensive Mobility Training (IMT). Twelve participants with chronic, mild-to-moderate, Traumatic Brain Injury (TBI) causing significant locomotor impairment, who meet these specific criteria, will be recruited. Location and nature of neural insult will be determined by multimodal Magnetic Resonance Imaging (MRI) exam. All participants will receive 3 hours of rehabilitation per day for 20 days, focusing on gait and balance. Locomotion and balance will be comprehensively tested prior to IMT, after 10 days of IMT, and then again after the full dose of IMT. This study will determine the feasibility of this intervention in the population of TBI patients, allow an estimate of effect size and provide initial information on possible neural predictors of success. Furthermore the investigators will be able to determine whether the dosage of 10 days is sufficient or whether significant improvements are made with 20 days of the intervention.

Inclusion Criteria:

1. greater than 3 months post-TBI (as defined by INTRuST criteria) and no longer receiving care as an inpatient in a rehabilitation facility.
2. the ability to follow simple three-step commands;
3. the ability to communicate presence and location of pain;
4. the ability to sit independently without back or arm support for five minutes;
5. the ability to stand with support of a straight cane, quad cane, or walker for 2 minutes;
6. the ability to walk 10 meters with maximum 1 person assisting;
7. presence of motor deficits (determined by clinical assessment of paresis);
8. age ≥ 18;
9. ability to give consent or have a acceptable surrogate capable of giving consent on subject's behalf

Exclusion Criteria:

1. unable to ambulate 500 feet prior to TBI;
2. history of serious chronic obstructive pulmonary disease or oxygen dependence;
3. severe weight bearing pain;
4. lower-extremity amputation;
5. non-healing ulcers on the lower-extremity;
6. renal dialysis or end stage liver disease;
7. legal blindness or severe visual impairment;
8. severe arthritis or orthopedic problems that limit passive ranges of motion of lower extremity (knee flexion contracture of -10°, knee flexion Range of Motion < 90°, hip flexion contracture > 25°, and ankle plantar flexion contracture > 15°);
9. history of deep venous thrombosis or pulmonary embolism within 6 months
10. uncontrollable diabetes with recent weight loss, diabetic coma, or frequent insulin reactions;
11. severe hypertension with systolic greater than 200 mmHg and diastolic greater than 110 mmHg at rest;
12. intracranial hemorrhage related to aneurysm rupture or an arteriovenous malformation (hemorrhagic infarctions will not be excluded);
13. history of severe uncontrolled seizure disorder;
14. other neurological conditions such as multiple sclerosis or Parkinson's Disease;
15. pain that is scored greater than 5 out of 10 on a visual analog scale;
16. any factor contraindicative to MRI examination (e.g., cardiac pacemaker/ defibrillator, pregnancy, aneurysm clips, insulin pump, metal fragments in the body).
17. any other health problems judged by their screening physician to put the client at significant risk of harm during the study