Cancer mortality rates are usually reported as composite age-adjusted rates. These rates have been declining modestly since the 1990s. However, these statistics (which represent a weighted average of all age groups) heavily emphasize the experience of the oldest Americans, for whom mortality rates are the highest. As a result, trends emerging in younger Americans can be concealed. As an alternative to age adjustment, the authors examined cancer mortality rates stratified by age and birth cohort. This analysis revealed that every cohort of Americans born since the 1920s has experienced a progressive decline in cancer mortality rates at every age for which data is available. These results suggest that the efforts of researchers and practitioners to more effectively prevent, detect, and treat cancer have had a significant impact on our population's cancer mortality risk over the past half century. For details, see the article by Kort and colleagues on page 6500 of this issue.