These two volumes present the methodology and results of an international research project on second language acquisition by adult immigrants. This project went beyond other studies in at least three respects: in the number of languages studied simultaneously; in the organisation of co-ordinated longitudinal studies in different linguistic environments; and in the type and range of linguistic phenomena investigated. It placed the study of second languages and inter-ethnic discourse on a firm empirical footing. Volume 1 explains and evaluates the research design adopted for the project. Volume 2 summarises the cross-linguistic results, under two main headings: native/non-native speaker interaction, and language production. Together they present the reader with a complete research procedure, and in doing so, make explicit the links between research questions, methodology, and results.