Party division in Peru is a constant event and has become an expected feature of Peruvian parliamentary politics. For instance, in 2016, the elected Congress was composed of six parliamentary groups, and at the moment of its dissolution, that number doubled. This article explores the factors that produce such rapid division in the Peruvian Congress during two parliamentary periods (2011–2016, 2016–2019). It argues, through quantitative analysis, that there is a direct and negative relationship between the fragmentation of parliamentary groups and party discipline due to party affiliation and the dynamics of subnational party competition.