A cross-sectional study investigated the shedding of zoonotic organisms (Campylobacter, Giardia, and Salmonella) and antimicrobial resistant generic E. coli in dogs that visited dog parks in southern Ontario. Logistic regression models were constructed to identify risk factors. Factors for the shedding of Campylobacter spp. included consumption of a commercial dry diet, exposure to compost, and age. Factors for the shedding of C. upsaliensis included outdoor water access and age. A risk factor for ampicillin resistance was attending a dog day care. For resistance to at least one antimicrobial, factors included attending a dog day care, breed size, consumption of a commercial dry diet and consumption of a homemade cooked diet. For multiclass resistance, exposure to compost, breed size, and consumption of a commercial dry diet were identified. Park was not significant in any model. Dogs that visit dog parks shed organisms that may pose a human health risk. / Canadian Institutes of Health Research (CIHR) Institute of Population and Public Health/ Public Health Agency of Canada Applied Public Health Research Chair awarded to J. M. Sargeant; Public Health Agency of Canada; Ontario Veterinary College Pet Trust Fund; and a grant to D. L. Pearl from the Canada Foundation for Innovation and the Ontario Research Fund.