The purpose of this content analysis was to examine in detail the nature and extent of messages about sex that are presented in the "family hour" on broadcast network television. The research sought to identify any patterns that exist in portrayals of sexual behavior as well as characters' talk about sex, using a sample of programming from the winter of 1996. In addition, the study assessed how messages about sexuality have changed over time by comparing winter 1996 programs to those aired in 1976 and 1986. The analysis examined the context that surrounds each portrayal and the extent to which messages about sexual risk or responsibility are presented. Results showed that the depiction of sexual content in family hour programming has increased consistently over the last 20 years--up 118 percent since 1986 and 270 percent since 1976. This pattern applies to the number of shows that include sexual messages as well as the amount of such messages that programs contain. The largest part of this overall increase involved depictions of sexual behaviors, which have multiplied nearly five-fold. Physical flirting and kissing accounted for more than 80 percent of this behavior, but 3 percent involved sexual intercourse; no such behavior was found in 1976 or 1986 samples. Messages about the risks and responsibilities associated with sex received only modest attention (9 percent); none of the examples of sexual intercourse included any reference to risk or responsibility topics. However, 29 percent of sexual interactions involving teens were presented in the context of a show that did reflect a thematic emphasis on issues of sexual responsibility. (Contains 25 references.) (EV)