Abstract: Chestnut blight presents an interesting model system for the studt of disease.  Using this system, infection and progression of the chestnut blight fungus (Cryphonectria parasitica) in a host population of American chestnut (Castanea dentata) were examined in two separate studies.  The first was an experimental study aimed at determining how artificial stem damage and defoliation affect probability of infection as well as how they affect tree growth.  The second study focused on what could be determined about disease progression through an examination of stem cross-sections.  For the experiment, 400 trees free of pycnidia were administered treatments of either control, stem damage, 75% leaf removal, or stem damage and 75% leaf removal.  Trees were examined one month later for incidence of disease and for differences in growth.  Incidence of disease after one month was too low to detect any difference between the treatments, however defoliation and stem damage did affect growth differently.  In the cross-section analysis, twenty stems from four disease classes were sampled, and growth rings were measured, as well as partial growth rings caused by the attack of C. parasitica.  Sample size was too small to detect any significant trends among the four disease classes, but the results do point out certain characteristics of cross-sections worth studying in larger quantities.