No social institution is more important in contemporary Russia than friendship. Russians view it as key to both personal flourishing and to politics. My book asks why and turns for answers to Russia’s political elites at the time when the modern Russian state formed. Most historical accounts of friendship hinge on a normative definition—as an affective connection between two equals. My approach is the opposite, taking the practices of historical agents as a starting point, to ask how, when, and why they referred to one another as “friend”. In the late 18th century, I argue, Enlightenment conceptions of civic virtue required members of the service nobility to reconceive of their allegiances and obligations as voluntary. Invocations of friendship served this end, becoming essential affective tools, intended to tie the nobility to the court. In the early 19th century, they became essential tools of opposition.