A current aim in forest products research is to efficiently modify wood to tailor it for specific end uses, such as hardening softwoods for flooring or softening wood in pretreatments for biorefineries. Research efforts in these areas are hindered by a lack of understanding of how wood modifications cause changes in bulk wood properties. Bulk wood properties derive from an ensemble of processes taking place at smaller length-scales, and therefore, to understand how wood modifications affect wood properties, techniques to characterize wood at these smaller length-scales are needed. To characterize wood at the cellular level, researchers at FPL, in cooperation with researchers at the University of Wisconsin, have developed a unique set of nanoindentation tools to probe the micron-size domains in wood cell walls. These tools account for the effects of edges near the nanoindents and assess the elastic and plastic properties of cell walls over a wide range of time-scales. These techniques are being used to understand wood modifications to improve current forest products and develop new products.