We develop a theory of the association between earnings management and voluntary management forecasts in an agency setting. Earnings management is modeled as a "window dressing" action that can increase the firm's reported accounting earnings but has no impact on the firm's real cash flows. Earnings forecasts are modeled as the manager's communication of the firm's future cash flows. We show that it is easier to prevent the manager from managing earnings if he is asked to forecast earnings. We also show that earnings management is more likely to follow high earnings forecasts than low earnings forecasts. Finally, our analysis shows that shareholders may not find it optimal to prohibit earnings management. Earlier results rationalize earnings management by violating some assumption underlying the Revelation Principle. By contrast, in our model the principal can make full commitments and communication is unrestricted. Nonetheless, earnings management can be beneficial as it reduces the cost of eliciting truthful forecasts.