Young European Socialists (YES), formerly the European Community Organisation of Socialist Youth (ECOSY), is an association of social democratic youth organisations in Europe and the European Union.

YES is the youth organisation of the Party of European Socialists (PES) and is a sister organization of the International Union of Socialist Youth (IUSY). The seat of the organisation is Brussels.

Full members status is held to the European Youth Forum (YFJ) which operates within the Council of Europe and European Union areas and works closely with both these bodies.

YES was founded as the European Community Organisation of Socialist Youth (ECOSY) in November 1992 in Oegstgeest/The Hague. The preparatory committee consisted of Philip Cordery (MJS, France), Joris Jurriëns (JS-PvdA, Netherlands), Jens Geier (Jusos, Germany), Giustina Magistretti (Italy), and Pascal Smet (Belgium).

Before 1992 the European activities had been coordinated inside IUSY, especially in the European Leaders Meeting.

The European Socialist Youth (ESY), founded in parallel, was only a weak organisation, a short time later renamed the European Committee, one of the IUSY continental committees.

The organisation's name was changed to Young European Socialists (YES) at the 11th Congress in Bommersvik in 2013.

Since the founding of ECOSY in 1992 until 1997, the presidency rotated simultaneously with the EU Presidency