This paper analyzes how factional conflict and intra-party organization affect a party’s likelihood of being involved in a ruling coalition. We focus on Italian parties (between 1946 and 2013) estimating their internal heterogeneity through quantitative text analysis of policy documents presented by factions during party congresses. The impact of inter-factional conflict has been investigated in interaction with intra-party rules showing that when the party leader is autonomous and can rely on powerful whipping resources to impose discipline, the party will credibly sticks to the coalition agreement, thereby reducing the negative effect of factional heterogeneity in coalition bargaining.