Agile software engineering methods have recently emerged as a new and better way of developing software as compared to the traditional methodologies. This book explores and determines the critical success factors of Agile software development projects using quantitative approach. The book compiled success and failure factors of Agile projects identified in the existing literature into a preliminary list of potential critical success factors. A survey was conducted among Agile professionals, gathering empirical data from 109 Agile projects from 25 countries across the world. The results revealed that only 10 out of 48 hypotheses were supported, identifying three critical success factors for Agile software development projects. The book should provide researchers and practitioners with insight on the comparative values of success factors, and might be helpful to those managers and professionals considering joining the Agile bandwagon.