Based on a novel database of kinship relations among the political elites of Chile in the nineteenth century, this thesis identifies the impact of family networks on the formation of political factions in the period 1828-1894. The sociological literature theorising the cleavages that divided elites during the initial phases of state formation has focused on three domains: 1) The conflict between an expanding state and the elites; 2) the conflict between different economic elites; and 3) the conflict between cultural and ideological blocs. This thesis develops a fourth approach referred to as Florentine, which builds on a tradition of historical and sociological research focused on the Italian city-states of the Renaissance. The Florentine approximation is elitist-focused and relational: elitist-focused because it imputes overwhelming power to the oligarchy vis-à-vis other groups in society, and relational because its analytical leverage comes from identifying the effects of networks on political outcomes. The most influential tradition in Chilean historiography sees nineteenth-century politics as shaped by the state-oligarchy opposition. Other approaches highlight the importance of economic sectors and ideological cleavages. In contrast, this thesis presents data demonstrating the importance of the family. The principal political conflict in nineteenth-century Chile consisted of neither the state versus the oligarchy, nor the mining versus the landed elites, nor the Liberals versus the Conservatives, but of elite families fighting other elite families. To develop this argument, this thesis utilised an original database with information on the family relations among all 1449 Parliamentarians, Presidents, and Ministers in the period 1828-1894. These data were combined with information on the electoral performance of all Parliamentarians over six decades. The analysis sought to infer the alignment of families during the civil wars of 1829, 1851, 1859 and 1891. Using social network analysis techniques, kinship clusters were identified, and the resulting groups were then contrasted against the electoral data. If a family cluster was well represented in Congresses immediately before the onset of violent conflicts, it was inferred that the family supported the pre-conflict regimes; where a family bloc increased its representation in post-conflict Congresses, it was concluded that its allegiance was with whatever administration took power after the conflict. Once the political allegiance of families was coded this way, substantive differences in the social status, geographic origin, and political party affiliation of the inferred sides were examined. If they did not differ substantially on these accounts but were differentiated by kinship, then it was concluded that the cleavage explaining the conflict at hand was familial. The results obtained using this procedure enabled a historical description of how elite factions formed in Chile. At its oligarchic core, the civil war of 1829 involved three large family clusters: a defeated cluster around the Vicuña clan, and two victorious clusters organised around the Irarrázaval and Vial clans, respectively. Upon the formation of the so-called Pelucón regime following the civil war, members of the Vial cluster became an internal opposition that would impact the subsequent emergence of political parties. In the years 1849-1851, the Vial and Errázuriz families established an alliance with the defeated faction of 1829 led by the Vicuñas and together formed the Liberal party. At its oligarchic core, the civil war of 1851 pitted the new Liberal party against families located near the Irarrázaval clan in the kinship network. 1859 was the only civil war with no clear familial cleavage because most core families sided against the government, which in turn had a strong base of support among bureaucrats and the bourgeoisie. The Liberal party broke apart during the civil war of 1891, which mirrored the old familial cleavage of 1829. The last chapter shows that the intra-elite divisions that structured conflict in the nineteenth century were abandoned at the turn of the twentieth century, upon the emergence of middle- and working-class parties. Whereas in the first century after independence, elites fought one another, now they all joined the same side of the political spectrum.