This paper studies the effects of within-firm political diversity on firms’ performance. Using data from campaign contributions of employees of publicly traded firms in the United States, we are able to construct measures of within-firm ideological heterogeneity. We then are able to identify local level measures of polarization using county level voting patterns and county level viewership of partisan news media. We merge those measures with firms’ performance data from Compustat. We use a difference-in-differences identification strategy and find that ideologically heterogeneous firms do perform worse during more polarized times compared to more homogeneous firms. This has important implications for our understanding of the consequences of political polarization beyond the political arena.