Christian missionaries engaged in ministry to Muslims aiming to bring more Muslims to the Christian faith over the last several decades. Their mission strategies devised partly based on the assumption that either conversion is an event or a process that happens with interplay of various factors. For this reason, few conversions happened in Muslim communities where Christian missionaries conducted mass preaching and crusades by expecting quick response from Muslims; however, more conversion registered in areas where culturally relevant and long term ministry strategies were developed. This book, therefore, provides the conversion process and the major factors for conversion of the Arsi Oromo Muslims from Islam to Christianity by using the Lewis Rambo’s seven stage model. It also shows that more conversion happened in the rural village which is hostile environment for Christianity compared to the towns that enjoyed freedom of worship. The most important changes after conversion and how the churches engaged the converts (Muslim background believers) into the Christian community are analyzed.