[2] The son of Italian immigrants, Giannini grew up in Elmwood Park, a suburb of Chicago, and has three younger brothers.

He attended Fenwick High School in Oak Park, and received a bachelor's degree in psychology from North Central College in Naperville.

[3][4][5] From 1987 through 1989, Giannini served as a graduate assistant on coach Lou Henson's staff at the University of Illinois.

Giannini totaled a 168–38 record in seven seasons at Rowan, which included five NCAA Tournament appearances and three Final Four berths.

[6][7] On August 23, 2004, Giannini was hired as the eighteenth head coach of the La Salle men's basketball team.

During his last four years as head coach, La Salle was honored by the NCAA for having one of the best academic progress rates in the country.

After defeating twelfth-seeded Ole Miss in the third round, La Salle lost to Wichita State in the Sweet Sixteen.

It was also the program's deepest tournament run since 1955, when the Tom Gola-led Explorers lost in the national championship game.

Additionally, he supports Philadelphia Youth Basketball and Samaritan's Feet, which works to provide shoes to children around the world.