Prior to beginning his professional career, he played college baseball at Duke University.

Gallagher has also competed for the United States national baseball team.

Gallagher attended Peters Township High School in McMurray, Pennsylvania and Duke University, where he played college baseball for the Duke Blue Devils baseball team in the Atlantic Coast Conference of the National Collegiate Athletic Association's (NCAA) Division I.

[2] Gallagher played for the United States national baseball team in the 2011 Pan American Games, winning the silver medal.

This biographical article relating to an American baseball outfielder born in the 1980s is a stub.