Ahlgren has 4 Celtic Woman concerts.

Celtic Woman is a musical group from Dublin, Ireland comprising five Irish women with a repertoire that ranges from traditional Celtic tunes to modern songs. Current members include the five vocalists Méav Ní Mhaolchatha, Máiréad Carlin, Susan McFadden, Lynn Hilary, Alex Sharpe, and the violinist Máiréad Nesbitt. Deirdre Shannon sang with the group during Ní Mhaolchatha's pregnancy in 2005-2006. Hayley Westenra, a New Zealander of Irish descent, sang with the group during its 2006-2007 tour as its sixth member.