[8] The founding members were two liberal and distinctively pro-Europeanist parties: the Italian Radicals (RI), whose leading members included Emma Bonino (a former minister of International Commerce and Foreign Affairs), Riccardo Magi and Marco Cappato, and Forza Europa (FE), led by Benedetto Della Vedova, a former Radical elected in 2013 with Future and Freedom (FLI) and later transitated through Civic Choice (SC).

Angelo Bonelli, coordinator of the Federation of the Greens, had earlier proposed to the Radicals a joint list together with Progressive Camp (CP), a would-be party launched by Giuliano Pisapia, named "Ecology, Europe, Rights".

[9] However, Pisapia announced that he would not participate in the election and declared CP's experience over, while the Radicals organised +E and the Greens would form an alternative list named Together.

In early January 2018, Bonino and Della Vedova announced that +E would run as a stand-alone list, due to technical reasons associated with the new electoral laws.

[28] The slates included, along with Bonino and Della Vedova: David Borrelli and Daniela Aiuto, two MEPs both originally elected with the M5S; Federica Sabbati, a former secretary-general of the ALDE Party; and art critic Philippe Daverio.

[39] In October, also Fusacchia announced he was leaving the party, which was left with only one deputy, Magi,[40] who remained despited his early support of the government.

[44][45][46] During a national assembly in March, treasurer Valerio Federico suffered a motion of no confidence and Bonino left the party in protest.

The motion was supported by Magi, Igor Boni, Silvja Manzi, Piercamillo Falasca and Carmelo Palma, the first three leading members of Italian Radicals and the latter two formerly close associates of Della Vedova.

[56] In the run-up of the 2022 general election, +E broke up with Action, as the latter decided not to align with the centre-left coalition led by the PD, but to form a stand-alone list with Italia Viva (IV).

[64] +E's electoral lists included also some newcomers and/or independents, such as Marco Bentivogli (a reformist trade unionist), Dorina Bianchi (a social-conservative),[65] Gianfranco Librandi (L'Italia c'è and ex-IV),[66] Enzo Peluso (ex-PRI)[67] and Franz Ploner (Team K).

Magi, a long-time Radical, was elected secretary and Pizzarotti, a former mayor of Parma for the M5S turned independent who had recently joined the party, was appointed president.

[72][73][74][75][76] In March 2024, in the run-up of the 2024 European Parliament election, the party gave birth to a broad, liberal and pro-Europeanist list named "United States of Europe", along with the Italian Radicals, Italia Viva, the Italian Socialist Party, the European Liberal Democrats and Volt Italy, in order to overcome the 4% electoral threshold.