The Italian Democratic Socialists (Socialisti Democratici Italiani, SDI) was a small social-democratic party in Italy. The party was led by Enrico Boselli, and was considered to be the direct continuation of the Italian Socialists, the principal party formed on the ruins of the historical Italian Socialist Party (PSI). SDI merged with several descendants of the historical party to form the modern day Socialist Party on 5 October 2007.
In the 1999 European Parliament election, the first important election contested, the Italian Democratic Socialists scored 2.2% and elected two MEPs. For the 2001 general election, the party formed an unsusual alliance with the far-left Federation of the Greens called 'The Sunflower', which was disbanded early after the election, because of the bad electoral result (only 2.2% together, while the combined result of the two parties in 1999 was 4.0%) and political disagreements. In the 2004 European Parliament election, two SDI Member of the European Parliament were elected on the The Olive Tree ticket.
In 2005 SDI entered in alliance with the Italian Radicals, a libertarian party, forming the Rose in the Fist electoral list. In 2006 Socialist Unity of Claudio Signorile joined the SDI, while some members of NPSI, as Donato Robilotta, founded the Reformist Socialists and joined directly the Rose in the Fist.
In the 2006 general election the list scored only 2.6%, much lesser than the electoral sum of the two parties before the alliace (Radicals alone took 2.3% in the 2004 European Parliament election). It seemed that the Radicals lost voters in their strongholds in the North to Forza Italia, while the Socialists lost ground in the South, where they are more radicated, to the The Olive Tree parties (see electoral results of the Rose in the Fist).
The proposed Constituent Assembly lead to a new social-democratic party, which will put an end to the Socialist diaspora and which at one point was considered a possibly form a federation with the Italian Radicals (whose leader Emma Bonino insisted that "the Rose in the Fist" is not dead at the congress), the European Republican Movement and the Federation of Italian Liberals.
Only Ottaviano Del Turco supported the entry of SDI in the Democratic Party and Enrico Boselli was re-elected secretary of the party with 784 votes out of 787 and only 3 abstentions. Thus the party is strongly united behind Boselli, Villetti and Intini, and Del Turco may well remain in the party.
On 5 May 2007, Ottaviano Del Turco and his supporters formed a new group named Reformist Alliance, in order to try to bring the Socialists into the Democratic Party (PD). On 23 May 2007, Del Turco entered as independent in the promoting committee of the PD, while remaining member of the SDI. The following day, Enrico Boselli announce the exclusion of Del Turco from the party, a decision which was described by Del Turco himself as "Stalinist". The Reformist Alliance went on to join the Democratic Party on its founding congress on 14 October 2007.