view of the immense importance of yellow rust in Pakistan, as well as at the regional and international levels, a comprehensive analysis of both aspects of Puccinia striiformis f. sp. tritici and wheat resistance were needed and is the primary objective of this book. The current information about recent yellow rust populations in Pakistan compared with Nepal were also connected to information of rust populations in other regions of the world. Information on virulences and their distribution and frequency is very useful for breeding programs to develop wheat cultivars with effective resistance. The resistance genes identified in the wheat materials through gene postulation and molecular markers, especially those with adult-plant resistance, will be useful for breeding wheat cultivars with durable resistance.