This book is about change in the Roman Catholic community in England and Wales. It argues that in the post-war years of economic growth and expanded educational opportunities, Catholics born in Great Britain achieved rates of upward social mobility comparable to those of the general population. In so doing there arose a 'new Catholic middle class', likely to be crucial for the future of Roman Catholicism in England and Wales. However, since one quarter of English Catholics were first-generation immigrants who had experienced some downward mobility, it could not be said that English Catholics generally had experienced a 'mobility momentum' relative to the rest of the population. Apart from the effects of social change, post-war Catholicism was also transformed as a result of the religious reforms legitimated by the Second Vatican Council in the early 1960s. The net effect of these social and religious forces on English Catholicism was the dissolution of the boundaries which had formerly defended a 'fortress' church in a hostile world. The book identifies this, inter alia, in the widespread heterodoxy of belief and practice, and in the decline of marital endogamy and communal involvement.