Leinster have confirmed Stuart Lancaster will leave the province at the end of the season and join Top 14 side Racing 92.
The former England coach has signed a four-year contract to become director of rugby at the Parisian outfit, with current head coach Laurent Travers moving upstairs after being appointed chairman of the club's management board.
Lancaster joined Leinster as a senior coach in September 2016 and became a hugely popular figure, helping the province win a Pro14 and European double in 2018. They have since won three more domestic titles and reached two Champions Cup finals.
"I will be eternally grateful to Leo [Cullen], Mick [Dawson] and Guy [Easterby] and the whole Leinster organisation for the opportunity they gave me and my family back in 2016," said Lancaster.
"Initially it was for just one season and here I am entering my seventh and that is a reflection on all the players past and present I have worked with and the people of Leinster and Ireland who have made me and my family feel so welcome.
"I have always wanted to challenge myself as a coach in different ways and the opportunity to coach in France at a club like Racing 92 is an exciting one and I will look forward to that challenge when it comes.
"In the meantime, I really want to give everything to the whole of Leinster Rugby and the supporters in the next eight months as I feel we have more to come as we drive towards the exciting challenge ahead both in the URC and in Europe."
"Stuart has helped us to grow at all levels, both through his work with the senior team and his willingness to get involved with underage teams as well as clubs around the province, where he is always so generous with his time."
Prior to joining Leinster, Lancaster spent four years as England head coach. They finished as Six Nations runners-up four times in a row under his stewardship and he departed after they failed to qualify from their Rugby World Cup pool in 2015.
Lancaster also worked on a consultancy basis with the Atlanta Falcons, British Cycling, the English FA and with Counties Manukau in the Mitre 10 Cup in New Zealand.
Leinster head coach Cullen added: "Stuart has been a brilliant asset to Leinster Rugby since he joined us in 2016. He has helped us to grow at all levels, both through his work with the senior team and his willingness to get involved with underage teams as well as clubs around the province, where he is always so generous with his time.
"I think there has always been a realisation that Stuart would move on to a new challenge at some stage. For that reason, we feel fortunate to have had him here for as long as we have, and we wish him, his wife Nina and kids Sophie and Dan the very best in their next adventure with Racing 92 in France.
"We have had some great days together and, on a personal level, Stu has been an incredible support. We will all miss him but I am very excited and enthused to go on and try to achieve further success this season as a group."