Clay was introduced into single-walled carbon nanotube (SWNT)/epoxy composites to improve nanotube dispersion without harming electrical conductivity or mechanical performance. Unlike surfactant or polymer dispersants, clay is mechanically rigid and known to enhance the properties (e.g., modulus, gas barrier, and flame retardation) of polymer composites. Combining nanotubes and clay allows both electrical and mechanical behavior to be simultaneously enhanced. With just 0.05 wt % SWNT, electrical conductivity is increased by more than four orders of magnitude (from 10(-9) to 10(-5) S cm(-1)) with the addition of 0.2 wt % clay. Furthermore, the percolation threshold of these nanocomposites is reduced from 0.05 wt % SWNT to 0.01 wt % with the addition of clay. SWNTs appear to have an affinity for clay that causes them to become more exfoliated and better networked in these composites. This clay-nanotube synergy may make these composites better suited for a variety of packaging, sensing, and shielding applications.