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The Tenrecidae of Madagascar comprises at least 26 species, all of which are endemic to the island. These species originated from founder stock that colonised from mainland Africa some 60 million years ago and underwent an extensive adaptive radiation to fill a wide range of niches. This paper reviews recent data to determine the energetic and reproductive differentiation that has occurred within this mammalian family and the factors that influenced evolutionary processes. Resting metabolic rate (RMR) is associated with body mass and ecological factors. Small tenrec species that occur in eastern and central forests have RMRs similar to those found in tropical shrews, whereas dry forest and arid zone species have lower than expected RMRs and enter daily or seasonal torpor. The body temperature (Tb) of non reproductive tenrecs is significantly lower than that of all other insectivores except golden moles. However, RMR and Tb are elevated in all species of tenrec during pregnancy and lactation, and this may be associated with an improvement in homeothermy. Intraspecific variation in gestation length may be related to the occurrence of daily torpor during pregnancy, a phenomenon previously recorded only in heterothermic microchiropteran bats. Adaptations for increased reproductive output within the constraints of a uniformly long gestation length and low Tb are discussed. It is concluded that a suite of ecological, climatic and phylogenetic traits are associated with the wide energetic and reproductive differentiation found within the Tenrecidae.