To estimate multipliers linking surveillance of salmonellosis, campylobacteriosis, and Shiga toxin–producing Escherichia coli (STEC) infections to community incidence, data from a gastroenteritis survey and other sources was used. Multipliers for severe (bloody stool/long duration) and milder cases were estimated from probabilities of doctor visit, stool test, sensitivity of laboratory test, and reporting to surveillance system. Australian annual community incidence rates per 100,000 population were estimated as 262 for salmonellosis, 1,184 for campylobacteriosis, and 23 for STEC. Emerg Infect Dis. 2008;14(10):1601-9.