This article contrasts developments in two types of agrarian societies in Indonesia which differ substantially with respect to ecological, historical and socioeconomic conditions. Java is characterized historically by wet rice cultivation and a relatively high population density. The "Green Revolution", aiming at an intensification of the production of rice as a commodity, has brought an end to the process of agricultural involution that had been observed for the colonial period, and has lead to an accelerated socio-economic differentiation. A growing number of poor rural households are threatened by progressive impoverishment. For these households, subsistence production is becoming increasingly important as the only means of ensuring survival. Precolonial Simalungun is characterized by swidden agriculture and a low density of population. In contrast to Java, the commercialization of agriculture has not been forced upon peasants in the Simalungun highlands, but has developed through a "free interplay of the market forces". The combination of subsistence production and commodity production has strengthened the economic basis of all peasants. Commercialization has so far not lead to an impoverishment of economically weaker households. More recently, however, trends toward an intensification of differentiation processes have become more noticeable.