The Radicals were originally a left-wing group, but, starting with the emergence of the French Section of the Workers' International (SFIO) in 1905, they shifted gradually towards the political centre.

Radicals defended traditional peasant farmers and small craftsmen against the new rival economic projects of the 19th century, socialist collectivism and capitalist big business alike.

Ledru-Rollin obtained only 5% of votes at the December 1848 presidential election, which was won by Louis-Napoléon Bonaparte, who launched a coup, ending parliamentary democracy in favour of a Second Empire.

At the end of the 1860s, they advocated with the Belleville Programme (supported by Léon Gambetta) the election of civil servants and mayors, the proclamation of the so-called "great liberties", free public teaching and the separation of church and state.

The first elections in February 1871 returned a majority of monarchists belonging to two distinct factions, conservative-liberal Orléanists and Catholic-traditionalist Legitimists, but these were too divided to reach an agreement over the type of monarchy they wanted to restore.

Georges Clemenceau was the leader of the Radical parliamentary group, who criticized colonial policy as a form of diversion from "revenge" against Prussia and due to his ability was a protagonist of the collapse of many governments.

In 1901, an Act on the right of association was voted and the various individual Radicals organised themselves into a political party in order to defend their governmental achievements from the Catholic Church's influence and the traditionalist opposition.

Delegates represented 476 election committees, 215 editorial boards of Radical newspapers and 155 Masonic lodges as well as lawmakers, mayors and municipal councillors.

The party was composed of a heterogeneous alliance of personal fiefdoms, informal electoral clubs, masonic lodges and sections of the Ligue des droits de l'homme (Human Rights League) and the Ligue française de l'enseignement (French League of Education, an association dedicated to introducing, expanding and defending free, compulsory and non-religious primary education).

Émile Combes took the head of the Bloc des gauches cabinet and led a resolute anti-clerical policy culminating in the 1905 laic law which along with the earlier Jules Ferry laws removing confessional influence from public education formed the backbone of laïcité, France's policy of combatting clericalism by actively excluding it from state institutions.

From then on, the Radical-Socialist Party's chief aim in domestic policy was to prevent its wide-ranging set of reforms from being overturned by a return to power of the religious right.

The cabinet led by the Independent Radical Georges Clemenceau (1906–1909) introduced income tax and workers' pensions, but is also remembered for its violent repression of industrial strikes.

During World War I (1914–1918), the Radical-Socialist Party was the keystone of the Sacred Union while the most prominent Independent Radical Georges Clemenceau led the cabinet again from 1917 to 1919.

Additionally, the Radical-Socialist Party had thought before 1914 that its old adversaries among the Catholic, monarchist and traditionalist right had been weakened once and for all, instead these emerged reinvigorated by World War I.

However, the Radical-Socialists gradually drifted to the right, moving from left-Republican governments supported by the non-participating Socialists to a coalition of "Republican concentration" with the centre-right Independent Radicals and the more socially-conservative liberal parties in 1926.

[19] The second Cartel des gauches won the 1932 legislative election, but its two main components were not able to establish a common agenda and consequently the SFIO chose to support the second government led by Herriot without participation.

After the 29 September 1938 Munich Agreement which handed over Sudetenland to Nazi Germany in exchange for what proved to be a temporary peace, Daladier was acclaimed upon his return to Paris as the man who had avoided war.

Following the 23 August 1939 Molotov–Ribbentrop Pact between Nazi Germany and the Soviet Union, Daladier engaged in an anti-communist policy, prohibiting the Communists activities and the party's newspaper, L'Humanité.

Daladier would eventually resign in March 1940 and take part in the new government of Paul Reynaud (leader of the main centre-right liberal party, the Democratic Alliance) as minister of National Defense and of War.

Daladier was arrested and tried in 1942 by the new regime (see the Riom Trial) which accused him as well as other political leaders such as Socialist Léon Blum and conservative Paul Reynaud of being morally and strategically responsible for the loss of the Battle of France.

The Fourth Republic was characterized by constant parliamentary instability because of divisions between major parties over the Algerian War, which was officially called a "public order operation" until the 1990s.

On 13 May, European colonists seized the Governor-General's building in Algiers while Opération Résurrection was launched by the right-wing insurrectionary Comité de Salut Public.

De Gaulle, who had deserted the political arena for a decade by disgust over the parliamentary system and its chronic instability (the système des partis which he severely criticized), now appeared as the only man able to reconcile the far-right and the European settlers, which were threatening a coup d'état, with the French Republic.

Henceforth, the Radical Party began to be known as valoisien, from the location of its national headquarters at the Place de Valois in Paris, in order to distinguish it from the MRG.

They allied with the Christian Democrats in the Reforming Movement in order to propose another way between the Common Programme's parties and the Presidential Majority led by Gaullists.

After the failure of the alliance with the Christians Democrats into the Reforming Movement, the Radical Party maintained its influence by participating in the foundation of Giscard d'Estaing's Union for French Democracy (UDF) in 1978.

During the 2002 presidential election, François Bayrou presented himself as a candidate for the UDF while the Radical Party supported his rival Jacques Chirac (RPR).

The party soon started to attract other centrists (as Jean-Louis Borloo, Renaud Dutreil, Véronique Mathieu and Françoise Hostalier) and even some anti-Sarkozy neo-Gaullists (as Serge Lepeltier and Alain Ferry).

During the 8th European Parliament, the single Radical MEP Dominique Riquet sat with the Alliance of Liberals and Democrats for Europe (ALDE) group as part of the UDI.