This study describes certain aspects of the life history of Chamaeleo pumilus (Gmelin) and of C. namaquensis A. Smith. Reproductive potential, population size, territorial structure, thermoregulation, behaviour, and other ecological relationships of these chamaeleonids in dynamic equilibrium with their vastly different habitats are considered. The viviparous, arboreal C. pumilus lives mostly in mesic areas of southern Africa. The aforementioned ecological considerations of the oviparous C. namaquensis have never been studied. This ground-dwelling species inhabits semi-arid and arid areas of southern Africa.