In this chapter, we present an overview of the ongoing efforts in the Sustainable Materials Research Laboratory at Rowan University related to providing society with alternative (poly)phenolics that are derived from xylochemicals (wood-derived building blocks). The xylochemicals utilized are molecules that we currently obtain, or have the potential to obtain, from lignocellulosic biorefineries, including pulp and paper mills and fermenters. As lignin is known as Earth's most prevalent aromatic biopolymer, our approach has strategically focused on designing, synthesizing, and testing monomers, oligomers, and resins containing lignin-derived units (such as guaiacyls, coniferyls, and courmaryls), as well as other bio-based molecules (e.g., cardanol and furandicarboxylic acid). Similar to nature, we strive to engineer materials that aid in sustaining life, withstand environmental stress factors, and serve multiple needs. Testing has included spectroscopic, rheological, thermomechanical, thermogravimetric, mechanical, and toxicity measurements to fundamentally understand the structure-processing-property-toxicity relationships of our novel systems. As a result of this work, we are generating a valuable library of xylochemical-based (poly)phenolics and their functionalized derivatives for use in high-performing polymer applications, including coatings, adhesives, composites, and membranes.