This book provides an in-depth and comprehensive examination of the scholarly debate regarding the sources used by the author of Acts (Luke). The author critically surveys various hypotheses put forward by scholars, primarily from the 19th to the mid-20th centuries, regarding the written and oral sources underlying the writing of Acts. He also highlights that modern scholarship places greater emphasis on Luke's redaction of his sources than on simply discovering the 'raw sources' behind the text. This book aims to map the current state of this scholarship, review key arguments, and assess the historical reliability of Acts based on the identified sources. This book is essential for students of New Testament studies because it provides an objective summary of the evolution of academic thought on how Acts was composed.