In 1976 Gagliardi became bass player for the half-British, half-American original lineup of Foreigner that also included founder Mick Jones, Lou Gramm, Al Greenwood, Ian McDonald and Dennis Elliott. Originally named Trigger, the band was signed to Atlantic Records at the urging of A&R executive John Kalodner leading to the release of their debut album, Foreigner, in March of 1977. That album established them as a major force with top twenty hits Feels Like the First Time, Cold as Ice and Long, Long Way From Home.
The band went into a whirlwind year that saw them building their audience from small venues to playing in front of 200,000 at California Jam. Their second album, Double Vision, was released in June 1978 and continued their assault on Top 40 radio with Hot Blooded (1978 / #3), Double Vision (1978 / #2) and Blue Morning, Blue Day (1979 / #15).
In 1979 Gagliardi parted ways with Mick Jones and Foreigner prior to the recording of their third album, Head Games, over creative differences and was replaced by Rick Wills. Ed went on to form the group Spys with his former Foreigner bandmate Al Greenwood. The band recorded two albums, Spys and Behind Enemy Lines.
He played his Rickenbacker bass guitar left-handed even though he was a naturally right-handed. He claimed he did that because of his devotion to Paul McCartney as bass playing inspiration.
He died on May 11, 2014 at age 62 after an 8 year battle with cancer.