We develop a novel methodology for studying the causal impact of announcement timing. Our methodology uses firms’ earnings announcements and leverages quasi-exogenous variation attributable to the specific day-of-week on which a calendar month begins. We refer to the resulting variation in announcement timing as “calendar rotations,” which are uncorrelated with proxies for announcement content. In applying our methodology, we show announcements moved forward by calendar rotations receive heightened media and investor attention, and experience greater earnings announcement premia. Taken together, our study details a method for studying how the timing of information flows impacts outcomes of interest to financial economists.