The Introduction explains the book’s intention to look at the religious history of the mid-seventeenth century in the context of the history of the Church of England and its earlier Reformations. Given that recent historians have emphasized that there was no single clear Church of England orthodoxy in the pre-war period, and have mostly ceased to use the term ‘Anglican’ altogether to describe pre-war conformists, it does not seem to make sense to describe the religious upheavals of these years as the destruction of a coherent established church. The book will instead propose that these events should be studied as an extended argument over the identity of the Church of England, and how it should be reformed, that involved a wide range of religious opinions. The use of the term ‘second Reformation’ to describe this phenomenon, and the rationale behind including the Laudian movement of the 1630s as part of this process, are explained. A final ‘Note on Terminology’ explains the meaning and rationale of several new terms introduced in the book to describe some of the phenomena discussed therein, and explains the rejection of the terms ‘Anglicanism’ and ‘Restoration settlement’ as anachronistic and/or misleading.