National censuses are rarely interested in those who know and use two or more languages, and they seldom make available statistics that reflect the bi- or multilingualism of their population. The author recounts how, over the years, he researched how many bilinguals there are in various countries. He contacted national statistical offices and census bureaus, studied their data, and perused national and transnational reports. He also interacted with official statisticians, who answered his questions and sent him unpublished data. And sometimes he went on specific quests to hunt down particular numbers or percentages that were being passed around. Here he concentrates on the results he obtained for the United States, Canada, Switzerland, and France. He ends with the holy grail many have been searching for – the proportion of bilinguals in the world. He gave an estimate back in 1982 – about half of the world’s population – and discusses how, with time, even 65 percent was proposed by some. Understanding why that was so was an adventure in its own right.