Theory, historiography and empirical evidence suggest that agriculture is the key to economic development. This paper examines the extent to which productivity advances in British agriculture in the period 1620-1850 were driven by technological progress. Measuring technology by patents and new book titles on agricultural methods, the results indicate that technological progress has played a significant part in productivity advances. Furthermore, the results show that research effort has permanent growth effects, consistent with the prediction of Schumpeterian growth theory.