The first chapters give a brief historical overview of the reasons for why this migration occurred, and the situation the European migrants entered to when they arrived in Latin America, such as the nations' colonial past. Then, the book provides a broad overview of the different forms of assimilation that occurred after different waves of migration occurred. Assimilation was influenced by the different reasons that people migrated -- such as to prosper from the coffee plantations of Brazil. The author attempts to provide a comparison of the various complex interactions between the new groups in different nations. The book evolves chronologically, examining how different 'injections' of new ethnic groups changed the composition of Latin America as a whole. Although all nations are discussed, if only parenthetically, because 79% of all migrants to Latin America between 1851 and 1924 settled in Argentina and Brazil, much of the book is focused on these nations, along with Chile, Paraguay, and Uruguay.

The book ends with a review of contemporary migration, and a general discussion of why human migration occurs. It examines the theory of equilibrium and the theory of historic-structuralism and tests their validity in the historical Latin American context. Equilibrium theory suggests that mobile labor forces create a "leveling" or equality of "human well being" and ultimately make the world a more economically equal and diverse place (124). The historical-structuralism perspective examines migration as a product of "structural transformation" and social formations, such as the coming to power of different racial and class groups and the influence of industrialization on the economies of different nations (124). Mrner believes these different theories offers some insight to explain mass migrations but also cautions the reader that non-economic and political influences had a profound influence on the period he chronicles.

This book is rather dry in terms of its presentation of historical information and sociological theory, perhaps because it was originally commissioned as a study by UNESCO, and was not originally intended to be read by the wider public. But learning about immigration to Latin America, and how it affected the racial and class structures within different nations, helps a reader becomes more aware of the social diversity of the region, and gain a better understanding of why some nations are more economically and politically stable at present than other Latin American nations. The book strives to put a human face on a now-often forgotten aspect of Latin American history. Usually, the ability of immigrants to make a positive contribution to the land to which they immigrated ultimately "depended more upon the socioeconomic structure of the receiver country" than upon the personal characteristics of the immigrants (84). The potential of a nation to become stronger because of immigration, Mrner writes, is contingent upon its social permeability and openness to change, not upon the educational or economic status of the migrants -- an important caveat to keep in mind during the present debate upon immigration in America.