My dissertation examines how study abroad transformed education and society in early modern Europe. My works centers on Poland, a region often considered peripheral by contemporaries and scholars alike. Through combining three case studies of representative individuals with a database of Polish students, I examine how study abroad in Italy and northern Europe in the sixteenth century inserted Polish humanists into the Republic of Letters. Their close personal and scholarly ties with prominent figures like Erasmus, Philipp Melanchthon, Paolo Manuzio, and Justus Lipsius not only nurtured their scholarly interests in classical learning, but also advanced their courtly, ecclesiastical, and academic careers after their return to Poland. Patterns of study, publication, and alumni networks united foreign-educated Polish humanists into a community of intellectuals at home and abroad. Education played a particularly important role in the intellectual and social life of middling nobles and burghers. The Polish political system of a nobles' democracy allowed elites to enjoy disproportionately greater political power, religious freedom, and economic control than their peers in Western Europe. Middling nobles and burghers used study abroad to acquire the intellectual tools and cultural capital to achieve social mobility and greater political participation in sixteenth-century Poland. These Poles used their humanist education abroad to transform a political environment in which they played second fiddle to nobles whom they considered intellectually inferior. The students achieved this by redefining the meaning of nobility itself. Like Renaissance humanists before and after them, these Poles used the concept of virtus (personal excellence) to argue that learning was a constituent part of true nobility alongside birth. Besides reconceiving nobility, these humanists sought to reform and establish educational institutions within Poland to solve political infighting and the religious strife caused by the Reformation. To capture the myriad dimensions of study abroad, I combine the qualitative methods of intellectual and cultural history with quantitative approaches like social network analysis and prosopography, drawing on my database of all Polish students who studied abroad in the sixteenth century. My work thus both reinserts Poland into early modern history and provides new perspectives on the historical phenomenon of study abroad.