Inclusion Criteria:
* Have weakness on at least one side of my body.
* No injury to my unaffected side in 6 months.
* Be cleared by a physician to participate in this study.
* Have had a non-penetrating TBI at least 2 years ago. A non-penetrating injury is an injury where my skull remained closed and no object entered it.
* Have enough strength to use a hemiwalker or walker.
* Be between 18-65 years of age.
* Be medically stable for at least 6 months before enrolling. This means that I have not had an emergency room visit, hospitalization, or medical procedure (such as a surgery) during this period of time.
* Able to walk 10 yards with minimal assistance without an ankle-foot orthosis (brace)
* Able to respond to and tolerate surface stimulation, as determined by study staff
* Have the ability to communicate in English.
* Have stable blood pressure.
* Be willing and able to give informed consent.
* Be able and willing to comply with study procedures, verbal instructions, and follow-up requirements.
Exclusion Criteria:
* Have must have not had physical or occupational therapy or treatment for a balance disorder within 30 days prior to study enrollment. I must not participate in physical or occupation therapy throughout the duration of the study to avoid affecting the study results.
* Have any medical issues that affect my unaffected side (such arthritis, fracture, etc.).
* Have skin issues that would prevent me from being able to use the surface stimulation (such as a open wound or rash).
* Have a pre-existing condition that may make it difficult for me to participate in exercise. (uncontrolled hypertension as described by a physician, heart disease, abnormal heart rate or rhythm, or congestive heart failure).
* Have been hospitalized for heart attack, heart surgery or acute heart failure within 3 months of enrollment in study.
* Have an implanted medical or metallic device.
* Reduced sensation in my lower limbs and stimulation locations.
* Have Botox injections in my legs up to 3 months prior to enrolling.
* Have physical therapy for walking.
* Have uncontrolled seizure disorder (such as epilepsy)
* Have nervous system-related issues (for example Parkinson's disease, multiple sclerosis).
* Major changes to my medications throughout the study
* Have bone or muscle issues unrelated to traumatic brain injury that interfere with my walking or limit my range of motion in my legs.
* Be currently pregnant. Because of potential risk to the fetus, women of child bearing potential will be required to have a pregnancy test before they can enroll in this study. If I am female, and have a positive pregnancy test, I will not be enrolled.
* Have any other medical conditions that my doctor or physical therapist feels would affect my ability to use the stimulation or participate in walking training TMS Specific - Exclusion (those with these exclusions can still participate in other parts of the study)
* I have a history of seizure disorder or have a close family member (parent, brother, sister, or child) who has a seizure disorder.
* I have had unexplained fainting spells.
* I have had an active migraine headaches.
* I have a past or current history of ringing in the ears (tinnitus) or severe hearing problems.
* I am currently taking or withdrawing from any medication that would increase my risk of seizure (determination made in consultation with study physician).
* I have a history of alcohol or drug abuse in the prior 3 years.
* I have nerve damage outside of my brain or spinal cord (such as in an arm or leg).
* I am unwilling to participate in TMS.
