The influence of mother-tongue interference is examined on the basis of data from two tests at different levels of English proficiency: a commercial-college level, covering 4-5 years of English studies, involving a composition and translation test, and a preuniversity level, covering 7-8 years of English studies, with a multiple-choice test. A distinction between choice problems and organization problems pinpoints differences in the learning of English between Finns and Swedish-speaking Finns. The difference in errors made by Finns and Swedish-speaking Finns is analyzed; attention is focused mostly on article and prepositional errors, errors of subject-verb concord, errors of subject-verb word order, and spelling and vocabulary errors. The influence of the different test-types is also discussed. The results indicate that there may be a difference in language-learning strategy between the two language groups. The volume concludes with a 444-item bibliography of error analysis, contrastive linguistics, language acquisition and language learning, and language testing, together with a list of other bibliographies. (Author/CLK)