The present study is an attempt to give a description of how temporal and modal meanings are expressed in Vietnamese, and to relate the description to English by way of translation correspondence. The study is, therefore, a contrastive work on Time and Modality in Vietnamese and English. It is hoped that Vietnamese students might find in this work some kind of help that may facilitate their study of English grammar as regards time and mood. In chapter 1, the author presents a brief history of foreign language teaching in Vietnam, and the role of English as a foreign language in the country at present. He also discusses problems confronting Vietnamese teachers and students in teaching and learning English and states the aims of the study. Next, the structure of the Vietnamese verb-phrase is discussed, with a view to giving the reader some idea of how auxiliaries operate in Vietnamese. In chapter 2, a description of temporal expression in Vietnamese is presented, with emphasis on the uses of the so-called "time auxiliaries". Also, time adverbs, time clauses and questions with time in Vietnamese are discussed. Chapter 3 deals with modal expression in Vietnamese. In this chapter special attention is given to the uses of the modal auxiliaries. Attempts are then made to describe the so-called "attitudinal disjuncts" and conditional sentences in Vietnamese. In chapter 4, implications for teaching time and modality in English to Vietnamese students are given. The author suggests some teaching points, which, through the present contrastive work, are likely to be some of the most difficult areas for Vietnamese speakers and therefore should be given the most particular attention.