The survival of the small-farm sector in the process of agricultural modernization in Latin America has been a concern for many authors and institutions. It is generally believed that the small-farm sector is bypassed in the process of agricultural development. The authors analyze modernization of bean; maize cropping systems in Southern Colombia. Prices, production practices and profitability are compared for 1975 and 1989. By means of a production function, the effects of allocative efficiency, technical efficiency and technical change on productivity and profitability are analyzed. The observed changes reflect very well the price trends over the period. Between 1975 and 1989, total factor productivity increased by 50%. Bean/ maize producers almost doubled returns to land and labor. Increased technical efficiency had most effect on profitability, followed by technical change. Allocative efficiency had more impact on yields than on profitability because it was associated with high input costs. Considerable opportunities for further productivity increases were identified. Conclusions on the nature of the modernization process are drawn. Implications for agricultural policy, research and the role of the small farm in agricultural development are derived.