This article seeks to summarize the results of some studies on the structure and dynamics of the big domestically owned industrial companies and groups in five Latin American countries (Argentina, Brazil, Chile, Colombia and Mexico); and presents supplementary elements for placing them in an overall perspective. The studies include individual analyses of 46 leading companies (in Brazil, Chile and Colombia); and 15 economic groups with an industrial base (in Brazil and Mexico);, together with aggregated studies of such groups in Argentina, Brazil and Mexico. In all cases, the studies were based on specially arranged interviews, the review of statistical and documentary information, and data already processed in the relevant literature. The time-scale of the studies ranges from the formation of some big companies and groups in the early years of the century or the period of dynamic import substitution industrialization, up to the changes under way in the second half of the 1990s. Analysis is centered on the last decade: i.e., since the time when the structural reform processes were at their height in most of the countries whose big companies and groups are studied in this work. The article is divided into four sections. After the Introduction (section I);, some summary details of the business context in the five countries studied are given (section II);, after which the main structural features of the big companies and groups and their recent dynamics at the company, plant and group level are analysed (section III);. Finally, in section IV, the main challenges facing public policies in this respect and the positions taken in the current debate on them are set forth.