The Nationalmuseum in Stockholm holds a vast collection of Italian paintings dating from the High Middle Ages to the late Nineteenth century. The present catalogue offers the first results of the ongoing research of the approximately 900 paintings of which very few are previously edited. The paintings are discussed according to their historical provenance in order to give the reader a broader picture of the paintings' history. The collection reflects not just the tastes and pursuits of the early modern royal patronage but also the policies regarding acquisition in the Nationalmuseum during the first decades of the twentieth century. Ultimately, the catalogue offers a great insight into the reception of Italian art in Sweden during three centuries. Among interesting results, the research team has been able to discover never edited works by, for instance, Federico Barocci and Pietro da Cortona. The only existing version of Caravaggio's St John the Baptist in the Galleria Corsini in Rome, which is kept in the collection, has been successfully investigated by an Italian team and with a highly interesting attribution as a result.