Latino-majority congressional districts are far more likely to elect Latino representatives to Congress than majority-white districts. However, not all majority-Latino districts do so. This paper addresses this question and it investigates how the level of influence of political parties and interest groups in majority-Latino districts substantially shape Latino representation to the U.S. House of Representatives. I rely on five case studies and a dataset of candidates to open congressional races with a Latino population plurality from 2004-2014. The evidence indicates that groups and political networks are critical for Latino/a candidate recruitment, the organization of resources in a congressional district, the deployment of campaign resources on behalf of certain candidates and the eventual success of Latino candidates. The findings suggest that Latino descriptive and substantive representation are shaped by the wielding influence of political parties and interest groups.