Thermoset compositions and methods for forming three-dimensional articles via an additive fabrication process, and articles made therefrom are disclosed herein. In an embodiment, a composition comprises a first network-forming component comprising a first oligomer comprising a backbone and having at least 2 polymerizable groups, one or more first network monomers, and a first network initiator. The backbone of the first oligomer comprises a polyepoxide based on Bisphenol A, F, or S, a polyepoxide based on hydrogenated Bisphenol A, F, or S, a polycarbonate, or a polyimide. The composition may further comprise a second network-forming component.