In this study, an outbreak of Campylobacter jejuni gastroenteritis occurring at a boarding school was investigated using a retrospective cohort study and environmental health investigation. Thirty-five cases of gastroenteritis were recorded among 58 questionnaire respondents, with 14 of 18 persons submitting fecal samples having confirmed C. jejuni infections. Attendance at one evening meal was statistically associated with illness (ratio of proportions of 3.09; 95% confidence intervals: 1.21, 14.09; p = 0.02). There was no statistically significant association between any single food provided at the implicated evening meal and illness, suggesting that the potential cause of the outbreak was a cross-contamination event. Among the human isolates, two distinct restriction fragment length polymorphism-flaA subtypes were found. Results from subsequent multilocus sequence typing data were consistent with the flaA typing results. The study highlights the potential of cross-contamination as a cause of epidemic campylobacteriosis. The application of molecular techniques to aid epidemiological investigation of recognized C. jejuni outbreaks is illustrated.