A joining method and assembly for an aircraft. To improve the characteristics or permit hitherto impossible connections between thermoplastic and thermoset components, a multi-material joining method is disclosed in which a thermoplastic connecting region is formed on the thermoplastic component. The connecting region is connected to the thermoset component by interdiffusion. For this purpose, the uncured second component is brought into contact with the connecting region and heat is supplied. An interdiffusion layer is formed which fixedly connects the second component and the connecting region to one another and thus joins the first component to the second component.