This chapter provides a brief overview of the synthesis, properties, applications, and recycling processes of some selected thermoset classes. This is followed by a selection of bio-based building blocks and the description of their synthesis routes with a focus on sustainability. The subsequent chapter delves into thermoset recycling strategies. The thermoset classes include crosslinked polyolefins, formaldehyde resins, polyurethanes, epoxide resins, polycyanurates, unsaturated polyester and vinyl ester resins, benzoxazine resins, perfluorocyclobutane polymers, acrylate-based thermosets, hydrocarbon resins, and vitrimers. References for further reading are provided for each of these classes.