The sub-surface damage modes in carbon fiber/epoxy composite laminates after low-velocity impact were investigated. The effects of interlayers inserted between continuous fiber layers were evaluated on impact damage resistance of composites. These interlayers were made of short fibers and a tough polymer film, such as Kevlar fibers, Zylon fibers and poly(ethylene-co-acrylic acid) (PEEA) film. Optical and scanning electron microscopy was employed to study the impact damage mechanisms and their correlations with the interlayer reinforcements.