Barley Yellow Dwarf (BYD) is frequently occurring viral disease around the world including Pakistan. Results reported in this book is part of the project entitled "BYD threat assessment in Khyber Pakhtunkhwa and identification of resistant sources for wheat improvement" funded by Directorate of Science and Technology (DoST), Government of Khyber Pakhtunkhwa, Pakistan. Surveillance was carried out and current BYD prevalence, incidence, severity and disease impact were established in the region. BYD suspected samples were indexed using DAS-ELISA technique and PAV was the predominant serotype found in the region. Wheat sources for BYD resistance genes including Bdv1, Bdv2 and Bdv3 were characterized. Information reported in this book will be highly useful to wheat researchers around the world.