Of the many variables affecting foreign language learning, the learner's first language is of especially great importance. The recent emphasis on language learning processes rather than linguistic products has given a new slant to what was earlier known as transfer studies. This book is concerned with the foreign language learner's underlying processes. It is based on data from Finland showing the differences between Finnish-speaking and Swedish-speaking Finns learning English. These two groups are close to each other culturally and educationally, though they are linguistically quite different. The results of the study reveal clear differences between learning a foreign language that is related and a language that is unrelated to the learner's first language. The basic importance of perceived similarities between the first language and the target language is stressed. The book analyses the different ways in which the learner's knowledge of the first language and other languages affect the processes of comprehension and production. A concluding section of the book sums up the relevance of its findings for foreign language teaching.