In this paper, the authors examine the role of management in agricultural productivity, by evaluating a mobile-phone based agricultural advice service provided to farmers in India. Demand for advice is high; and advice changes practices, increasing yields in cumin (28%) and cotton (8.6%, for a sub-group receiving reminders). Information spreads, as non-treated farmers with more treated peers change practices and lose less to pest attacks. Though willingness to pay for the service is low, the value of the information externality exceeds the subsidy that would be necessary to operate the service.