The purpose of the poliomyelitis vaccine evaluation program in the field trial of 1954 was to seek a measure of the prophylactic effect of the preparations of vaccine to be used, the only assumptions 'being that the experimental background was sound and that the vaccine was to be antigenic and noninfectious. The undertaking meant the acceptance of a public and scientific trust to provide, so far as possible, an objective analysis and unprejudiced appraisal of data obtained from numerous study areas. It must be fully realized that the evaluation program was not a tightly knit operation carried on by a single group of investigators. Rather, it was a widespread series of investigations that the vaccine evaluation center at the University of Michigan sought to integrate by obtaining uniform acceptance of instructions and procedures and, thus, to maintain uniformity of understanding and performance and completeness and accuracy of investigation and report.