This paper provides empirical evidence of the importance of firm attention to macroeconomic dynamics. We construct a text-based measure of attention to macroeconomic news and document that attention is polarized across firms and countercyclical. Differences in attention lead to asymmetric responses to monetary policy: expansionary monetary shocks raise market values of attentive firms more than those of inattentive firms, and contractionary shocks lower values of attentive firms by less. Attention also mitigates the effects of macroeconomic uncertainty on firm performance. In a quantitative rational inattention model that is calibrated with this new text-based measure, inattention drives monetary non-neutrality. As average attention varies over the business cycle, so does the efficacy of monetary policy.