This research work focuses on the study of the adaptation of naturalist novels for the theatre. A widespread phenomenon in the XIX century, adaptations for the theatre promised glory to novelists attempting a literary career. Moreover, they marked a shift towards a renewal of the theatre itself in all possible ways: acting, staging, and themes. For this reason, a comparative study of several European naturalist authors (Zola, Goncourt, Capuana, Lemonnier, Galdós, Hardy) makes it possible to build a wide general picture and identify common practices. Furthermore, the analysis carried out during the research also highlights significant socio-literary trends emblematic of the construction of a capitalist and democratic society opening the way to the XX century.