We have determined the thermal resistance for transferring heat between individual single-walled carbon nanotube devices and solid substrates. Using sapphire and comparing our results to previous results obtained from SiO2, we find that the resistance is dominated by interfacial resistance rather than the spreading resistance of heat for diffusing into the substrate. Our results are in agreement to a recent model for the thermal resistance of nanoscale constrictions. Our results suggest that relatively short contact lengths (~10β30 nm) to a typical solid should be sufficient to transfer heat efficiently into carbon nanotubes, underscoring the potential of carbon nanotubes for nanoscale thermal management