Scholars have emphasized the need to deepen investigation of intraparty politics. Recent studies look at social media as a source of information on the ideological preferences of politicians and political actors. In this regard, the present article tests whether social media messages published by politicians are a suitable source of data. It applies quantitative text analysis to the public statements released by politicians on social media in order to measure intraparty heterogeneity and assess its effects. Three different applications to the Italian case are discussed. Indeed, the content of messages posted online is informative on the ideological preferences of politicians and proved to be useful to understand intraparty dynamics. Intraparty divergences measured through social media analysis explain: (a) a politician’s choice to endorse one or another party leader, (b) a politician’s likelihood to switch off from his or her parliamentary party group; and (c) a politician’s probability to be appointed as a minister.