This article examines the influence of radical flank actors in shifting field-level debates by increasing the legitimacy of preexisting but peripheral issues. Using network text analysis, we apply this conceptual model to the climate change debate in the United States and the efforts of Bill McKibben and 350.org to pressure major universities to “divest” their fossil fuel assets. What we find is that, as these new actors and issue entered the debate, liberal policy ideas (such as a carbon tax), which had previously been marginalized in the U.S. debate, gained increased attention and legitimacy while the divestment effort itself gained limited traction. This result expands theory on indirect pathways to institutional change through a discursive radical flank mechanism, and suggests that the actual influence of Bill McKibben on the U.S. climate debate goes beyond the precise number of schools that divest to include a shift in the social and political discourse.