In the 2012–13 season Connacht's second tier side, the Connacht Eagles began competing in the British and Irish Cup, with Carolan serving as the team's head coach. He performed this role for two seasons, before being appointed to succeed Mike Ruddock as head coach of the Ireland under-20 team in October 2014. Carolan coached the side in three Six Nations and two World Championships, with the team's runner-up finish in the 2016 World Championship their best ever performance in the tournament.