In this paper we show that social fragmentation can trigger increased electoral competition and improved provision of public goods. We test this using large-scale data on family networks from over 20 million individuals in 15,000 villages of the Philippines. We take advantage of naming conventions to assess intermarriage links between families and use community detection network algorithms to identify the relevant clans in all of those villages. We show that there is more public goods provision and political competition in villages with more fragmented social networks, a result that is robust to controlling for a large number of village characteristics and to alternative estimation techniques. Using original survey data collected in 284 villages after the 2013 local elections, we also show that fragmented villages are associated with a broader distribution of political influence.