This study traces the development of a rubella outbreak; 16 clinical and one sub-clinical case were detected. Overall, the incidence of infection was higher for males than females. Susceptibility rates determined by the absence of primarily IgG antibodies indicated that class association, social contact, and preexisting susceptibility patterns influenced the differences in attack rates seen among the classes. In spite of a higher susceptibility caused in part by the number of foreign students enrolled, no infections occurred in the graduate student population. Concern for the spread of rubella to susceptible students and personnel within the dental school, among adjunct dental assistant and hygiene programs and others at the adjacent medical school and hospitals, led to a comprehensive immunization policy. All dental and medical personnel, regardless of clinical contact, must present proof of immunity or be immunized.