The paper sets out to identify the key factors behind changes in the number of farms in Poland during the country’s transition to a market economy. More than 1.2 million farms abandoned agricultural production at the time, according to Fałkowski. Despite this, an excessive fragmentation and overpopulation of farms are still believed to be the key barriers to the development of Polish agriculture, the author says. The paper uses data collected during censuses in rural areas in 1996 and 2002. The research is based on two methods, descriptive analysis and econometric analysis based on what are called probit models and the Heckman procedure. The results obtained by the author show that farms in areas with a less favorable agrarian structure and a positive balance of migration displayed a greater tendency to abandon agricultural production. Access to nonagricultural sources of incomes, in turn, slowed down the outflow of farmers to other sectors of the economy, Fałkowski says. This process is important for agricultural policy makers because it contradicts the popular belief that programs for the diversification of agricultural incomes have a positive influence on the rate of structural changes, Fałkowski concludes.