Inclusion Criteria:

• Age 18 years or older.
• Size and limb proportions capable of fitting in the exoskeletal device :
• Height between 1.55 m (5 ft, 1 in) and 1.92 m (6 ft, 3 in).
• Femur length between 37.5 cm (15 in) and 43.125 cm (17.25 in).
• Body mass no greater than 114 kg (250 lb).
• Non-ambulatory or poorly-ambulatory. In this study, "non-ambulatory" is defined as a person who cannot walk, or is classified with a Functional Independence Measure (FIM) Gait score 1; "poorly ambulatory" is defined as a person with FIM Gait 2- 6, who may be able to walk short distances with or without braces or stability aid, or may be able to walk with assistance of one person, but whose primary means of mobility is a manual or power-operated wheelchair.
• Sufficient upper extremity strength and coordination to balance using a appropriate stability aids, such as a rolling walker or forearm crutches, during exoskeleton walking.
• Present with SCI and NLI C5 or lower, with AIS A, B, C or D (as per the International Standard for Neurological Classification of SCI, ISNCSCI), who are non-ambulatory or poorly ambulatory.
• Chronic SCI: at least 6 months post-injury, and preferably post-injury more than 1 year.
• Sufficient bone health for walking with full weight-bearing without undue risk of fracture, as determined by each subject's personal medical doctor, and approved by each site's medical supervisor.
• Passive range of motion (PROM) at shoulders, trunk, upper extremities and lower extremities within functional limits for safe gait and use of appropriate assistive device/stability aid.
• Skin intact where interfacing with robotic device.
• MAS for spasticity score 3 or less in lower extremities.
• Blood pressure and heart rate within established guidelines for locomotor training:
• At rest: systolic 150 mmHg or less, diastolic 90 mmHg or less, heart rate 105 bpm or less.
• During exercise: systolic 180 mmHg or less, diastolic 105 mmHg or less, heart rate 145 bpm or less.
• Ability to tolerate an upright standing position for 20 min, passive or active, without being lightheaded or having a headache.
• Sufficient responsiveness to FES in the quadriceps, hamstrings, tibialis anterior, and gastrocnemius, as defined by MMT in response to stimulation of 3 or greater on a 5-point MMT scale. Note that this is specifically for Study 2, but is included in Study 1 in order to economize study resources regarding enrollment, training, and assessment, as previously discussed.
• Access to a wireless internet connection. Note that is required only for Study 3, but is included in Study 1 in order to economize study resources regarding enrollment, training and assessment, as previously discussed.

Exclusion Criteria:

• Heterotopic ossification that, in the opinion of the site medical supervisor, would place the subject at undue risk for fracture.
• Inability to follow instructions.
• Colostomy bag.
• Women who are pregnant or attempting to become pregnant during the course of the study. Note that a pregnancy test will be required and must be negative for all women prior to enrolling in the study, and will be additionally required and must be negative every four weeks during the course of the study protocol.
• Any disease, concomitant injury, or condition that interferes with the performance or interpretation of the protocol- specified assessments.
• Insufficient availability to complete study.
• Any other issue which, in the opinion of the investigators or medical supervisor, make the subject unsuitable for study participation.