With its sister volume, this book is a must for anyone, academic, pastor, or mission practitioner, interested in knowing how Christianity was considerably expanded in the 20th century, through churches' mission and missionary work, and was transformed into World (or Global) Christianity. The book is divided into two parts. The first part contains the introduction-background reading for the reports of the study process produced by the IMC Centenary Study process. The second part of the book includes 13 regional reports. Contributions from all over the world analyse and evaluate the impact-or the absence thereof-of the IMC and the CWME from 1921 until today.