In 1950, Paul Lazarsfeld wrote a paper entitled "The Obligations of the 1950 Pollster to the 1984 Historian." I think we should pay attention to his injunction. In fact, looking back at my research over the years, including my dissertation on the 1953 Konrad Adenauer election, the Spanish youth survey (the first national sample survey in Spain) in 1960, the study of Spanish entrepreneurs in 1959-1961, and the many surveys I did during the Spanish transition to democracy, it is obvious that today the main value of those studies is for the historian. Thus, one criterion in planning research should be how much our work will help the historian twenty-five or fifty years later to understand what happened in the past. In my work on the breakdown of democracies in the 1920s and 1930s, the rise of totalitarianism, and the origins of the Spanish Civil War, I always wished for the wealth of public opinion research that we have for a small number of countries since the late 1940s. Unfortunately, technological changes are making much of the data collected in the era of the IBM punched card inaccessible to contemporary researchers. Indeed, I worry about the future accessibility of some of the data being collected today in light of the inevitable changes that will occur in computer coding and storage.