Persons with spinal cord injury (SCI), particularly those with injuries above T6 (Hi-SCI), are unable to effectively regulate core body temperature (Tcore) due to interruption of motor, sensory, and sympathetic pathways. Interruption of sympathetic pathways limits central regulation of vasodilation and sweating for increasing heat loss and vasoconstriction for decreasing heat loss. Thus, when exposed to ambient heat, limited control of cutaneous vasodilation and sweating impairs the ability to maintain a constant Tcore. Persons with Hi-SCI often find themselves in hot environments for prolonged periods during social, religious, or work functions, especially during warmer seasons or when in hot climate zones. They report rapidly progressing to feeling “overheated,” uncomfortable, and fatigued during even limited exposure to conditions considered as mildly hot by able-bodied (AB) controls. During these times, their dramatic rise in Tcore can reach hyperthermia (≥38°C) and, if allowed to progress, can lead to heat stroke, causing seizures, loss of consciousness, and potentially death. Interventions that address the increased risk for heat-related illness in persons with SCI are limited. Therefore, continuing development of our feedback-controlled ”smart” cooling vest and testing its safety and efficacy to sufficiently dissipate body heat to compensate for thermodysregulation, is absolutely vital to minimize the adverse effects on health and quality of life that most Veterans with Hi-SCI experience during exposure to warm temperatures. The goals of this pilot study are to: 1) further develop and test the safety and tolerability of a self-regulating cooling vest in AB participants, and 2) determine the efficacy of the cooling vest to provide protection from an excessive rise in Tcore and thermal discomfort during warm exposure in Veterans with Hi-SCI. Five AB participants and ten participants with Hi-SCI (C4-T2, AIS A-B) will be recruited for study. AB participants will be observed to ensure the safety of the vest, which will be determined by assessing skin temperatures and subjective thermal sensation beneath the vest during 2 hours of warm exposure (35°C). In participants with Hi- SCI during 2 hours of warm exposure (35°C), a repeated measures experimental design for [two-conditions (wet vest, no vest)] is being proposed to demonstrate the efficacy of the cooling vest to attenuate the expected rise in Tcore and thermal discomfort. Primary Objective (Safety): In a warm thermal chamber (35°C), AB participants will wear the wet cooling vest at maximal setting for 2 hours in the seated position to determine: (1) minimum skin temperatures beneath the wet cooling vest, and (2) subjective comfort of the wet cooling vest (safety testing). Primary Hypotheses: AB participants will demonstrate (1) All skin temperatures beneath the vest will be ≥20°C. (2) All participants will report a thermal sensation (TS) ≥ “cool” (not “cold” or “very cold”) (Zhang 9-point T...