The editor of the""Teen Guide"" series, also author of the similar Safe Sex (1988), presents a historical overview that is mostly biological and statistical in scope. Nourse, a physician, advises living defensively and offers a calm, balanced approach to sexuality. While seeing abstinence as a sensible possibility, he admits that ""for most young people, 'no sex at all' is not going to work very well forever."" Attention to definitions and delineations is prominent in the quick-reference approach here: ""technical words"" in bold letters are fully defined in the text, often intrusively--and unnecessarily, since they are also in the glossary. Some choices for inclusion are odd--""heterosexual"" and ""homosexual,"" but not ""condom""--but there is a matter-of-fact series of drawings showing how to put on a condom. The color photos are sometimes misplaced, but occasionally have commendable impact. Since there are only ten pages here on prevention, and since discussion of psychological issues is minimal, the book is mistitled; still, a useful, straightforward discussion of AIDS. Glossary, Index.