Children and adults employ different thermoregulatory strategies. Under heat stress, children rely more on non-evaporative heat exchange, while sweating is adults’ foremost heat-dissipation process. Several anatomical, physiological, and psychological factors can affect differential risk of thermal injury in the child versus the adult athlete. Children have greater surface-area-to-mass ratio, lower sweating rate, higher peripheral blood flow in the heat, and a greater extent of vasoconstriction in the cold. They can acclimatise to a similar extent but do so at a lower rate than adults. Differences in perceived exertion and thermal strain, cumulative experience, cognitive development, and decision-making capacity may negatively affect the youth athlete’s behaviour under competitive and other situations, possibly subjecting him or her to sub-par performance or to greater risk of thermal injury. However, except for limited environmental conditions, children in general, and youth athletes in particular, are physiologically capable of handling environmental challenges as effectively as adults.