The materials employed in this investigation were 769 translations from Swedish into English made by Swedish university students studying English. The principal objective was to study aspects of learner behavior (in treating English word order) to obtain information about the types of errors Swedish students commit in English production and attempt to explain the causes of them. It is hoped that such information will be useful in the preparation of instructional materials, as well as in fostering constructive re-evaluations leading to improved teaching methods. The approach of this investigation has been both theoretical and practical in nature. As a point of departure, a simplified form of contrastive analysis of the Swedish texts and model English translations was carried out. Information obtained in this way was used in predicting potential difficulties for Swedish learners of English and in hypothesizing errors that Swedish learners of English could be expected to commit. The hypotheses were later followed up by empirical research involving observations of learner behavior. Actual errors occurring in the student translations were recorded, analyzed, and classified taxonomically. Finally, attempts to explain the students' errors were made, and in these attempts knowledge about the two grammatical systems, Swedish and English, was utilized. (Author)