This paper explores the role of agriculture in Spain's contribution to the little divergence in Europe. On the basis of tithes, long-run trends in agricultural output are drawn. After a long period of relative stability, output suffered a severe contraction during 1570-1620, followed by stagnation to 1650, and steady expansion thereafter. Output per head shifted from a relatively high to a low path that persisted until the nineteenth century. The decline in agricultural output per head and per worker from a relatively high level contributed to Spain falling behind and, hence, to the Little Divergence in Europe. Output per worker moved along labour force in agriculture over the long run, supporting the depiction of Spain as a frontier economy. Institutional factors, in a context of financial and monetary instability and war, along climatic anomalies, provide explanatory hypotheses that deserve further research.