Explaining the Rapid Adoption of Tobacco 21 Policies in the United States.

In this issue of AJPH, Reynolds et al. (p. 1540) describe the process of passing the first Tobacco 21 (T21) policy that raised the legal age for the sale of tobacco products to 21 years in Needham, Massachusetts, in 2003 and the subsequent spread of T21 policies across the United States. T21 policies have proliferated faster than any other retail tobacco control policy and the reasons behind their rise are worth examining because they may offer clues for promoting other worthy policies that have low adoption. We use diffusion of innovation and multiple streams theories to explain the rise of T21 policies.