Comte’s role in the history of sociology remains a controversial issue. To assess his claim of being its founder, this chapter briefly reviews the previous attempts to establish a social science and shows how Comte synthesized them. The first part presents his own account. As a matter of fact, Comte, given his strong historical perspective, wrote extensively about this topic in 1822 and 1839. He focused on Montesquieu and Condorcet, highlighting their positive contributions and limitations, and on physiological Ideology, which aimed to derive sociology from biology. Although this initial approach is useful, it is also somehow one-sided: Comte, for instance did not mention Saint-Simon, despite having been his secretary for seven years. The second part offers a new perspective by exploring two research programs widely discussed at that time: the science of man and the moral and political sciences. This approach provides new insights into Condorcet and the Ideologues. However, both programs ultimately proved to be dead ends. In fact, the actual roots of social science trace back to political economy and conjectural history, two fields that developed significantly during the eighteenth century, especially in Scotland. Comte’s debt to the Scottish Enlightenment has been overlooked, but is extensive. Regarding political economy, he is usually remembered for his critical stance, but we thereby forget that he began reading Adam Smith and J.B. Say, and that sociology emerged from recognizing the limitations of political economy. As for conjectural history, this perspective helps explain the central role of social dynamics in Comte’s sociology: Hume, he said, guided him toward discovering the law of the three stages.