At the heart of this book lies an ambiguity about the word “mission”. At times the word has a rather restricted meaning where it refers mainly to work “on the foreign missions”. At other times, or for other people, its meaning is much more general: it refers not so much to a particular kind of work, as to a sense of being called upon to undertake some important enterprise, with a corresponding attitude of willingness to break new ground and to work on a new frontier, outside the established structures. The aim of this book is to bridge the gap between these two understandings of the word mission. The book acknowledges that the concept of mission has changed significantly and that dialogue with other religions and spiritual outlooks is not opposed to mission, but is a central aspect of it. The book also examines key entry-points into the whole notion of mission, including the processes of evangelization and inculturation. Throughout the book, important issues that face missionaries and missionary societies are teased out. These include the enormous social and economic problems faced by many countries, as well as cultural and religious pluralism.