From the Canadian Bishops:

The General Secretariat of the Synod of Bishops today issued the preparatory document for the XV Ordinary General Assembly of the Synod of Bishops which will take place during October 2018 on the theme “Young People, the Faith and Vocational Discernment”. Pope Francis has also published a letter to young people on the occasion of the publication of the preparatory document.

Link to the letter of the Holy Father
Link to the preparatory document