This chapter will briefly examine the two projects for historical dictionaries that the Royal Spanish Academy (RAE) carried out in the twentieth century. It will also consider the publication, during the twentieth and twenty-first centuries, of the historical dictionaries restricted to a specific geographical area (specifically those from Costa Rica, the Canary Islands and Venezuela). We then present the Nuevo diccionario histórico del español (NDHE) project. This native digital dictionary, still under development, was conceived as a lexical database to be exploited as a historical dictionary. Finally, we offer some reflections on the future of the diachronic lexicography of the Spanish language.