This report details a novel methodology for determining rates of sexua
l activity in schoolchildren. The method has been found to be acceptab
le to schools, parents and students, it receives a high level of co-op
eration, a low (1%) parental withdrawal, and a low number (3%) of inad
equate responses. A marked advantage of this method is the absence of
direct questioning about first intercourse which is often considered i
nappropriate within schools. Validation conducted by interview at the
time of the questionnaire and one year postal questionnaire follow-up
indicates that this method gives a good estimate of sexual activity fo
r school populations.