Courts and agencies can no longer afford to ignore the role of labor markets in evaluating mergers. In this paper, I show that understanding the economics of monopsony and the facts of labor markets should make us much more skeptical of the economic benefits of mergers generally. Mergers frequently harm the market for labor. That understanding also helps us to identify mergers that cause particular harm to workers. And it gives the agencies tools to try to mitigate those harms – not merely by banning the mergers, but by protecting labor unions and banning noncompetes, nonsolicitation clauses, and other barriers to exit.