Cellulose nanocrystals (CNCs) attract great interest as inexpensive bio-based fillers in polymer nanocomposites. These highly crystalline rod-like particles can be isolated from a variety of bio-sources. CNCs display extremely high elastic moduli (100-150 GPa) and a high tensile strength (~10 GPa). Due to their outstanding mechanical properties and low cost, CNCs represent an intriguing alternative to carbon nanotubes. Over the last 15 years, many polymer nanocomposites comprising CNCs have been studied in research laboratories around the world, involving different types of CNCs and a diverse range of polymer matrices. This research program seeks to develop robust, cost-effective, and scalable methods for the mixing and processing of nanocomposites of technologically relevant polymers and CNCs isolated from wood. The first aim is to devise approaches for the mixing of the two components that minimize the use of organic solvents and avoid surface modification of the cellulose, yet lead to the morphologies – percolating networks within the polymer matrix – that result in maximal mechanical reinforcement. The second aim is to identify conditions that allow for the melt-processing of the target materials without imparting mechanical damages to the cellulose on account of high shear forces. To this end, significant progress has already been made.