A survey was made to study the discrepancy between adult students' mathematical abilities and their opinions of these abilities. A test was composed which comprised 40 questions spanning mathematics from 10th year to first year college level; together with a questionnaire, it was sent to participants in adult education classes in physical and biological subjects and in nonscience classes, in city, suburban, and county areas. A small control group was drawn from the staff of Senate House, administrative headquarters of London University. The parameters derived from total scores were Residual Mathematical Age (RMA) and Retention. Women adult students were found inferior in Retention, although the younger women in the control group did not show inferiority. Retention was inversely related to education; time since mathematical education ended was of surprisingly little significance; and people retain more mathematics than they think they do. Distributions of RMA and Retention were strongly dependent on the type of course attended; people competent in mathematics appeared in physical science courses and absent from nonscience courses; women did not join classes demanding mathematical ability unless they were far above average. [Not available in hardcopy due to marginal legibility of original document.] (pt)