She began writing stories as a child and was encouraged by her English teacher at Durfee High School in Fall River.

[1] Eagan attended Smith College her freshman year, then transferred to Stanford University in Palo Alto, California, majoring in American Studies.

She served a "refining stint" as a senior writer at Boston Magazine, and returned to her column at the Herald, where she wrote regularly until July 2014.

[2][3] From 2014 to 2016, Eagan wrote a column at the Boston Globe's website about the Catholic Church, Crux, on spirituality and devotion to God.

[4] After the Globe shuttered the site, Crux began operating independently under editor John Allen with financial support from the Knights of Columbus, but parted ways with Eagan.