Part of a 20-year Yugoslav Serbocroatian-English Contrastive Project, this study is intended to make students, teachers, textbook writers, and scholars aware of elements in the system of English modals that might cause difficulties to the native Serbocroatian-speaking learner of English. An eclectic method of contrastive analysis consisting of three steps was applied: collecting facts about the meaning and structure of English modals, linking them with corresponding information about Serbocroatian verbs felt to be their counterparts, and looking for positive and negative interference resulting from similarities and differences in the two systems. The first seven chapters look at some general grammatical and semantic features of the modals, and the last chapter treats individual modals (shall, should, will, would, can/could, may/might, must, have to, ought to, am/are/is + to, need, dare, and used to) by stressing features that seem important for teachers and other interested parties. Bibliographies and a chapter on teaching modals to Serbocroatian speakers who are learning English are included. (MSE)