To identify trends in smoking initiation among persons aged 10 to 20 years that might reflect the impact of specific targeting of tobacco advertising to women. Data from the National Health Interview Surveys on age of initiation of smoking (survey years 1970, 1978, 1979, 1980, 1987, and 1988) were used to construct age-specific rates of smoking initiation for males and females aged 10 to 20 years from 1944 through the middle 1980s. The raw rates were smoothed to allow trends to be more easily identified. Information from 102,626 respondents was used. In 18- to 20-year-old women, initiation rates peaked in the early 1960s and steadily declined thereafter. In girls younger than 18 years, smoking initiation increased abruptly around 1967, when tobacco advertising aimed at selling specific brands to women was introduced. This increase was particularly marked in those females who never attended college (1.7-fold higher). Initiation rates for females younger than 18 years peaked around 1973, at about the same time sales of these brands peaked. After a steep postwar (1944 to 1949) decline, initiation rates in 18- to 20-year-old men did not decrease until the middle to late 1960s. Initiation rates for boys younger than 16 years showed little change during the entire study period. The tobacco advertising campaigns targeting women, which were launched in 1967, were associated with a major increase in smoking uptake that was specific to females younger than the legal age for purchasing cigarettes.