Farm size in industrialized countries grew significantly over the second half of the twentieth century. Using several econometric models, this article examines factors that influence farm size, the probability of an increase in farm size, and the intensity of farm growth. We find that farm structural characteristics, farmer's age, the existence of a successor, and spatial factors approximating urban influences have a significant impact on farm size, whereas human capital variables do not. This study considers a representative sample of 5,000 professional farms in the Midi-Pyrénées region between 2000 and 2007