This disclosure is directed to methods directly adhering epoxy-based, and other thermosetting surfacing films to solid thermoplastic surfaces and the structures derived or derivable from these methods. In some embodiments, the disclosure is also directed to composite structures comprising a thermoplastic substrate directly bonded to a thermoset(ting) surfacing film; wherein the direct bonding defines an interface between a thermoplastic surface of the thermoplastic substrate and a first surface of the thermoset(ting) surfacing film.