Objectives. We sought to describe long-term adolescent and young adult smoking trends and patterns. Methods. We analyzed adolescent data from Monitoring the Future, 1976 to 2005, and young adult (aged 18–24 years) data from the National Health Interview Survey, 1974 to 2005, overall and in subpopulations to identify trends in current cigarette smoking prevalence. Results. Five metapatterns emerged: we found (1) a large increase and subsequent decrease in overall smoking over the past 15 years, (2) a steep decline in smoking among Blacks through the early 1990s, (3) a gender gap reversal among older adolescents and young adults who smoked over the past 15 years, (4) similar trends in smoking for most subgroups since the early 1990s, and (5) a large decline in smoking among young adults with less than a high school education. Conclusions. Long-term patterns for adolescent and young adult cigarette smoking were decidedly nonlinear, and we found evidence of a cohort effect among young adults. Continued strong efforts and a long-term societal commitment to tobacco use prevention are needed, given the unprecedented declines in smoking among most subpopulations since the mid- to late 1990s.