Based on a data collection of 84 years of legislative activity of the Mexican Chamber of Deputies, we argue that the increase of the political plurality in the integration of the legislatures, has been a crucial element that influences the amendment and the approval of legislative bills, as well as the way the members of the Lower Chamber participate throughout the process of the presentation of initiatives. A series of institutional reforms like the creation of an official political party, the prohibition of the immediate re-election of legislators, the successive reforms in the formulas to choose popular representatives and the enhancement of electoral competition, produced changes in the integration of the political representation. From all theses changes we identify different historical patterns of behavior in Chamber of Deputies during the 20th Century.