The properties of fiber-reinforced composites made using epoxy resin formulations can be improved using modified epoxy resins. As epoxies are inherently brittle, they are toughened with reactive liquid rubbers or core-shell elastomers. Surface-modified silica nanoparticles, 20 nm in diameter and with a very narrow particle size distribution, are available as concentrates in epoxy resins in industrial quantities for the past 10 years. Some of the drawbacks of toughening like lower modulus or a loss in strength can be compensated when using nanosilica together with these tougheners. Apparently, there exists a synergy as toughness and fatigue performance are increased significantly. Some of these improvements in bulk resin properties can be found for fiber-reinforced composites as well. In this article, the literature published in the last decade is studied with a focus on mechanical properties. Results are compared, and the mechanisms responsible for the property improvements are discussed. A relationship between the improvements of the fracture energy of the cured bulk epoxy resins and the fracture energy of the fiber-reinforced composites could be established.