Since 2010, independent expenditures have grown as a source of spending in American elections. A large and growing portion comes from “dark money” groups—political nonprofits whose terms of incorporation allow them to partially obscure their sources of income. I develop a new dataset of about 2,350,000 tax documents released by the IRS and use it to test a new theory of political spending. I posit that pathways for anonymous giving allowed interest groups to form new networks and create new pathways for money into candidate races apart from established political parties. Akin to networked party organizations discovered by other scholars, these dark money networks channel money from central hubs to peripheral electioneering groups. I further show that accounting for these dark money networks makes previously peripheral nodes more important to the larger network and diminishes the primacy of party affiliated organizations in funneling money into candidate races.