By learning from nature and using bio-based building blocks we can engineer sustainable high-performance materials with improved functionality. Nanocelluloses have entered the marketplace as new ingredients for formulated chemical products, composites and engineering processing technologies. However, the surface chemistry of nanocellulose must be well understood and controlled in order to optimize the interactions, stability and compatibility with liquids, ionic species and polymers. This talk will summarize approaches from our lab to tailor nanocellulose to enhance thermal stability, colloidal stability (and rheology), hydrophobicity and crosslinkability. Tunability can be achieved either during nanocellulose production or through new surface modification routes. For example, we compare the properties of nanocellulose produced via hydrolysis with different acids vs. chemical and electrochemically-driven oxidation. Alternatively, polymer grafting, adsorption, oligosaccharide precipitation and water-based esterification offer straightforward routes to tweak surface interactions. While primarily focused on cellulose nanocrystals, we have recently extended our tannic acid + hydrophobe adsorption modification route to cellulose nanofibrils to improve their compatibility in epoxy resin composites. We believe that these efforts to control nanocellulose surface chemistry and assembly are crucial on the path towards the commercialization of greener next-generation technologies.