Book excerpt: How is the reliability of a hadith narrator established? What distinguishes an ‘authentic’ tradition from a ‘weak’ tradition? How authentic are our hadith collections? The study of hadith transmitters (‘ilm al-rijal) is one of the most important disciplines in the analysis of textual accounts. It focuses on evaluating the reliability of people who transmitted narrations attributed to Prophet Muhammad and his successors and aims to categorise traditions into graded levels of authenticity and reliability. This book is an English translation of Durus Tamhidiyyah fi al-Qawa‘id al-Rijaliyyah, a widely-used textbook in Islamic seminaries. Designed with beginners to the subject in mind, the book is written in a clear and succinct manner and includes numerous worked examples and revision questions at the end of each chapter. Among the topics investigated by the author are the methodology used to establish the reliability of narrators, the general classifications of reliability, the validity of a rijali expert’s view, the types of traditions, and the major hadith and rijal books.