After having displayed the four traditions of international sociological surveys (Eurobarometers, Values, ISSP and ESS), this chapter explains their common points (for example the same willing to replicate questions throughout time, indicators which must be decontextualised - out of a national context -, often complicated questionnaires, inevitable problems of translations into several languages) and their differences (for example in the kinds and wordings of questions). The end of the article shows the progress in knowledge these surveys have allowed to make. They are essential for clear and effective comparison between societies which till now was only based on monographic approaches. They allow us to go beyond stereotypes and theories built on impressions or even rich but too specific analysis. They very well highlight the salience of cultural differences between countries that globalisation doesn't easily reduce.