This thesis investigates liberal responses to French expansionism during Napoleon III’s Second Empire, focusing on three of its main imperialist ventures in the late 1850s and the 1860s: Algeria, a colony inherited from the times of Charles X, whose colonisation received a great boost in the 1860s; Cochinchina, the main step of France’s imperialism towards Asia; and Mexico, Napoleon III’s personal dream for France in America, started as the alleged greatest project of the Empire which, however, ended in great failure. The focus of this study is not on individuals generally acknowledged as main liberal thinkers, politicians or philosophers but on a group of less-celebrated individuals who developed their professional activity both in parliament (the Corps législatif) and the press. The aim is to highlight how liberal languages and discourses in their specific context contributed to the development and the shaping of liberal thinking and political culture in the 1860s with regard to imperial expansionism. This dissertation seeks to tie in with the historiographical trend which sees intellectual and political history not as distinct fields, but as two inseparable sides of the same coin. In a period in which the Second Empire was experiencing a process of increasing internal liberalisation in a number of political, social and economic fields, the Empire’s means of repression and social control were still active. Censorship was commonplace in 1860s France, making it very difficult for those opposing the regime to express their ideas and concerns. However, thanks to several steps made towards opening up the regime politically from 1860 onwards, opposition deputies—including especially the liberals—were able to express in parliament their claims and objections. Whereas some social issues remained difficult to tackle, I argue that liberals found in the Empire’s imperialist endeavours an appropriate space to channel their dissatisfaction with the Bonapartists’ way of conceiving, ruling and managing the country. The Second Empire’s colonial project on all continents fostered an intense ideological debate that transcended the borders of a simple partisan confrontation. It rather revealed the existence of two political cultures in quest of social legitimation: liberal and Bonapartist. This thesis aims to bring together a history of nineteenth-century French imperialist ventures and a history of modern liberal political culture. No scholarly works have focused on the way in which French liberal thinkers, politicians or publicists imagined their empire in the 1860s, how they responded to Napoleon III’s will to expand France’s power and influence across oceans and continents with an intensity never seen before. This dissertation contributes to filling in this gap by tackling the liberal response to French expansionism with regard to three thematic areas: the role of France in the world; trade and finances; and religion. European politics aside, overseas ventures marked France’s foreign policy in the 1860s. The Second Empire’s project to expand France’s influence in the world through various systems of domination and control over peoples on virtually all continents became an issue of political debate that all forces of opposition, namely liberals, could not escape. Imperialist ventures became an important issue of political debate under the Second Empire and acted as a sort of 'hegemony' that liberals needed to confront, either opposing or supporting it. In this thesis, I argue that they did so, taking the opportunity to use the debates on expansionism in their own favour. Through discussing a wide range of social, economic and political topics related to France’s imperialism in Africa, Asia and America during the 1860s, liberals succeeded in presenting to the public an alternative model of government to the one represented by the Bonapartists in power.