Private investment in agricultural R&D is growing rapidly, especially but not only in high-income countries. Public-sector investment is indispensable to ensure adequate research investments in areas of little or no commercial interest, such as "orphan crops" that smallholders grow on marginal land. An extensive body of empirical evidence confirms the high returns to public investment in agricultural R&D, whose benefits are felt through three main channels: higher farm incomes, increased rural employment, and lower food prices for consumers.