The role of foreigners in early modern Europe was inversely proportional to the attention received by Historiography. This is also the case of Spain. Although already from 1960 the Spanish scholar Domínguez Ortiz called attention to the gap on the study of foreign communities, only since the 1990s research has begun to study systematically the activities of foreigners in Spain. However, progress in this direction is still far from the extraordinary results achieved in other areas by modern historiography. This paper addresses the possible causes of this delay and it presents also an overview of the most outstanding contributions on the role of foreigners in the Spanish finance and trade, the army, the court, the administration and industry.