This thesis is an investigation of the molecular epidemiology of the bacterium 'Clostridium perfringens,' a causative agent of many animal diseases, including necrotic enteritis in poultry. We used both pulsed-field gel electrophoresis (PFGE) and multi-locus variable number of tandem repeats analysis (MLVA) to characterize this bacterium. Two-hundred and ninety eight ' C. perfringens' isolates were obtained from two barns on a chicken farm in Southern Ontario, and were typed using PFGE. There was little bacterial genetic diversity in these two barns, with only 8 major PFGE types and 17 subtypes found. The majority of 41 representative isolates from each of two barns were resistant to bacitracin, an antimicrobial commonly used on the farm. Additionally, we have developed a new MLVA protocol for 'C. perfringens ' and validated it on a collection of 54 epidemiologically unrelated isolates, providing a high degree of discrimination (Simpson's index of diversity = 0.975). Finally, an infection challenge experiment was carried out with different 'C. perfringens' isolates from field cases of necrotic enteritis to determine their potential to recreate the disease.