The paper discusses trends in ownership concentration in three principal stages of the food system: food retailing, food manufacturing, and selected inputs purchased by agricultural producers and by food processors. In each of these levels, the available information from North America, Western Europe, or global sources shows that sales concentration is increasing. An attempt is then made to assess the impact on performance of these concentration trends for final consumers and to a lesser extent for agricultural producers. Performance measures most of interest are the traditional ones derived from economic welfare analysis of imperfect competition. Market performance is analyzed one level at a time but the more difficult arena of vertical subsector performance is also examined. The current role played by public policies in ameliorating consumer and producer welfare as it is affected by the exercise of market power is also assessed. In general, competition laws that apply to horizontal conduct are more settled and more easily enforced than are public policies directed at vertical strategic conduct.