I measure the effect of social networks on politicians’ career development. In this paper I construct a unique data set that contains information on the social network of the entire electorate of a sovereign nation, the 15th-century Republic of Venice. I identify the careers of 2.500 married politicians from the period between 1400 and 1524. Analyzing this panel of data I provide evidence that marrying the daughter of a more central father significantly improves the husband’s career prospects in politics. Moreover, I show that this effect is independent from other characteristics of either families, like historical prestige, wealth or voting power (family size), and it is not biased by assortative marriages.