The book sets out to study the use of sentence connectors, in English and Spanish, focusing on three different written scientific discourse registers: the ones to be found in articles on scientific matters written for the specialists in the field or for the general public and in regular textbooks. The authors base their study on a large English-Spanish, Spanish-English linguistic corpus; and they characterize the three registers by analyzing three main features in text discourse organisation: textual cohesion, schematic structuring of information and thematic position. The first allows them to classify the sentence connectors found in the corpus and observe how they contribute to text cohesion both in Spanish and English. By means of the second, one can appreciate the global structuring of the three types of scientific discourse under scrutiny in both languages. And the third allows them to make a comparative study of sentence connectors, in the two languages, in order to bring to light the various kinds of thematic progression in Spanish and English scientific discourse.