This book is a synopsis of sixteen original articles on English in Science and Technology/ESP written by Rosemarie Gläser between 1978 and 1994 and published in different countries. They cover the author's main areas of research and constitute the four parts of the book: 1. Lexicology and Phraseology, 2. Text Linguistics, 3. Stylistics, and 4. Diachronic LSP Studies. Emphasis is placed on an integrated approach to genre analysis, which is based on extensive text corpora and which results in genre profiles. Each genre profile is characterised by communicative and linguistic features, including rhetorical and also aesthetic properties. The diachronic approach is illustrated by ESP genres of the 16th and 17th centuries.