Legalization has been debated for decades, but California’s Fall 2010 vote on Proposition 19 makes passage seem suddenly more plausible. Proposition 19, which would have legalized not only personal consumption but also production and distribution to supply recreational use, was defeated narrowly (53.5% to 46.5%). This article synthesizes several threads of evidence concerning public support for legalization in the U.S. to shed light on the likelihood some similar effort will pass in the future. The overall conclusion is noncommittal, but the exercise generates a number of insights. In particular, simple what-if exercises suggest that the effects of generational turnover and voting occurring in a presidential vs. an “off” year may be smaller than some thought. The concluding section translates some of the observations into implications for both proponents and opponents of marijuana legalization.