This is probably one of the most popular novenas in the Church.  The Novena begins on the day after the Solemnity of the Ascension, Friday of the 6th Week of Easter, even if the Solemnity of the Ascension is transferred to the 7th Sunday.  Pray it as a group or do it as an individual challenge.

You can find more information about this novena, including the printable text on the EWTN site here.