This book gives a description of the use of weak-forms in present-day English, based on the variety traditionally referred to as RP or Received Pronunciation. In spite of the fact that weakening the pronunciation of a certain number of very common word-forms in the language is a very typical feature of English with a long history in English linguistics, the subject has never been given a proper treatment detailed enough to explain the regularities and irregularities of the phenomenon. The present book is an attempt to fill this gap, inventorizing all the forms that may occur in RP, and reviewing all the major conditioning factors (phonological, morphological, syntactic and lexical) that may influence their use or non-use. Though the author is not committed to any particular linguistic school, his approach makes use of an important insight provided by Government Phonology which regards the process of weakening as one of reduction, rather than replacement. In the last chapter the book also takes the first steps towards a formalization of the process, preparing the ground for further theoretical discussions on the subject.The author, Rudolf Obendorfer, was a lecturer in English Phonetics at the University of Oslo from 1973 until his retirement in 1998.