The joint initiation of legislation is one of the most important forms of collaboration within Congress, and the nature of such relations may affect its responsiveness. Through social network analysis, this article analyses the evolution of cohesion and polarization of policy networks for the Chilean Lower House from 2006 until 2017, comparing those derived from all bills from those that emerge when considering only successful ones. Although scholars consider that initiation of legislation is mostly free of party discipline or policy gatekeeping, networks recovered from all bills despite being highly cohesive replicate the roll-call divisions during all years under analysis. Among networks derived from successful bills - those able to overcome policy gatekeeping, collaboration crosses the ideological divide. These results imply that agenda setting plays a different role on policy collaboration than on voting and emphasize the relevance of the partisan dimension in agenda setting influence presented by Tsebelis and Aleman. Whereas the institutional prerogatives in the Lower House did not change after 2006, the partisan configuration did, which might explain the different degree of polarization among networks of successful bills found before 2006 by other studies.