Chickpea is one of the most important leguminous crops grown in regions of southern Europe, Asia, the Middle East, and the United States. Ascochyta blight, caused by Ascochyta rabiei, is the most important foliar disease of chickpea. In favorable conditions, this disease can destroy the entire chickpea field within a few days. In this project the secreted proteins of Ascochyta rabiei have been characterized through one and two-dimensional polyacrylamide gel electrophoresis. This is the first proteomic study of the A. rabiei secretome, and a standardized technique to study the secreted proteome has been developed. A common set of proteins secreted by this pathogen and two isolates that exhibit the maximum and minimum number of secreted proteins when grown in modified Fries and Czapek Dox media have been identified. Population genetic studies of Ascochyta rabiei populations in North Dakota have been conducted using microsatellites and AFLP markers. Population genetic studies have shown that the ascochyta population in North Dakota has not changed genetically in the years 2005, 2006 and 2007, but the North Dakota population is different from the baseline population from the Pacific Northwest. The ascochyta population in North Dakota is a randomly mating population, as shown by the mating type ratio.