This article examines cholesterol-related knowledge, cholesterol-related behaviors, and plasma cholesterol levels in 12-24-year-olds, using data collected from four community-based cross-sectional surveys conducted 1979-1980, 1981-1982, 1985-1986, and 1989-1990. Participants included 1,552 individuals from randomly sampled households in two control cities (San Luis Obispo and Modesto, California) of the Stanford Five-City Project. Over the eleven-year study period, cholesterol-related knowledge improved in both control cities (P < .0002). Cholesterol-related behavior (P < .0003) and plasma cholesterol levels (P < .002) significantly improved only in San Luis Obispo (a college city with more 19-24-year-olds and a better-educated population than Modesto). in general, knowledge and behavior scores and plasma cholesterol levels were lower in these 12-24-year-olds than in 25-74-year-olds, although trends at all ages were similar over time and by demographic variables. Although the cholesterol-related interventions that began in the mid-1980s primarily targeted adults, these 12-24-year-olds' cholesterol-related knowledge improved (as did, to a lesser extent, their cholesterol-related behavior and plasma cholesterol levels). These findings have implications for upcoming youth-related cholesterol interventions.