This study investigates the thermal and mechanical properties of single-wall carbon nanotube (SWNT)-epoxy composites. The results show that SWNTs significantly enhance the thermal conductivity of epoxy. At 1 wt% SWNT loading, the thermal conductivity increases by 125% at room temperature, compared to a 45% increase for vapor-grown carbon fibers (VGCF) at the same loading. The enhancement is much greater for SWNTs than for VGCFs, indicating that SWNTs are more effective for thermal management. The electrical conductivity data show a percolation threshold between 0.1 and 0.2 wt% SWNT loading, which is much lower than for VGCFs. The Vickers hardness of the composites increases monotonically with SWNT loading, reaching a factor of 3.5 at 2 wt%. These results suggest that SWNT-epoxy composites have improved thermal and mechanical properties without the need for chemical functionalization of the nanotubes. The study also highlights the importance of SWNT dispersion and alignment in achieving these enhanced properties. The results demonstrate that a small fraction of SWNTs can dramatically improve the thermal properties of an epoxy matrix. Future improvements may result from chemical functionalization of the SWNTs to enhance the SWNT-matrix interaction and the creation of anisotropic thermal management composites via nanotube alignment.This study investigates the thermal and mechanical properties of single-wall carbon nanotube (SWNT)-epoxy composites. The results show that SWNTs significantly enhance the thermal conductivity of epoxy. At 1 wt% SWNT loading, the thermal conductivity increases by 125% at room temperature, compared to a 45% increase for vapor-grown carbon fibers (VGCF) at the same loading. The enhancement is much greater for SWNTs than for VGCFs, indicating that SWNTs are more effective for thermal management. The electrical conductivity data show a percolation threshold between 0.1 and 0.2 wt% SWNT loading, which is much lower than for VGCFs. The Vickers hardness of the composites increases monotonically with SWNT loading, reaching a factor of 3.5 at 2 wt%. These results suggest that SWNT-epoxy composites have improved thermal and mechanical properties without the need for chemical functionalization of the nanotubes. The study also highlights the importance of SWNT dispersion and alignment in achieving these enhanced properties. The results demonstrate that a small fraction of SWNTs can dramatically improve the thermal properties of an epoxy matrix. Future improvements may result from chemical functionalization of the SWNTs to enhance the SWNT-matrix interaction and the creation of anisotropic thermal management composites via nanotube alignment.