We present a continuing investigation of epoxies based on diglycidyl ether of bisphenol A cured with 2-ethyl-4-methylimidazole in the presence of the nonionic surfactant Triton X-100. Interest in this epoxy system is due partially to its potential application as a waterborne replacement for solvent-cast epoxies in E-glass-laminated printed circuit boards. The surfactant additive could potentially alter the interfacial properties and durability of composite materials. Previous studies revealed that the viscoelastic behavior of the cured epoxy is altered when it serves as the matrix in a glass-fiber-reinforced composite. The additional constraining and coupling of the E-glass fibers to the segmental motion of the epoxy matrix results in an apparent increased level of viscoelastic cooperativity. Current research has determined that the cooperativity of an epoxy/E-glass composite is also sensitive to the surface chemistry of the glass fibers. Model epoxy/E-glass composites were constructed in which the glass was pretreated with either 3-aminopropyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane coupling agents. Dynamic mechanical analysis was then used to create master curves of the storage modulus in the frequency domain. The frequency response of the master curves and resulting cooperativity plots clearly varied with the surface pretreatment of the glass fibers. The surfactant had surprisingly little effect in the observed trends in the cooperativity of the composites. However, the changes in cooperativity due to the surface pretreatment of the glass were lessened when the samples were prepared from waterborne emulsions. Moisture-uptake experiments were also performed on epoxy samples that were filled with spherical glass beads as well as multi-ply laminated composites. No increases in the diffusion constant could be attributed to the surfactant. However, the surfactant did enhance the final equilibrium moisture-uptake levels. These equilibrium moisture-uptake levels were also sensitive to the surface pretreatment of the E-glass.