Partisan networks are a crucial non-policy resource granting political parties the capacity to connect with voters. Party activists serve a variety of important party functions. Party activists provide a mechanism for reaching voters and implementing the electoral strategies defined by politicians. We distinguish ideological activists specialized in policy persuasion and territorial activists dedicated to serving the wants and needs of voters in their own communities. We rely on our surveys and in-depth interviews with politicians and local campaign managers to describe the size, structure, and type of activist networks in each country, emphasizing variation across and within countries. Our measures show symmetry in network size across Chilean party organizations in contrast to the larger size of the Peronist and even Radical networks in Argentina (compared to those of newer parties). Chilean partisan networks are also more connected with ideologically akin voters and more connected to richer voters than those of the Argentine PJ and UCR.