Ben Harvey has resigned as director of rugby at Jersey.
The 39-year-old, who has coached at Jersey since 2008, met with club officials on Wednesday to inform them of his decision to stand down.
Jersey are second-from-bottom of the Championship table, with three wins from 10 league games this season.
Harvey led Jersey during their remarkable rise through the leagues, taking the club from London One to the Championship.
"I have spent two days away from the Island considering my position and I asked for a meeting to be held on my return," said Harvey.
"In this meeting, I said that I had decided that in order to progress my career I needed to part company with the club, and was therefore resigning with immediate effect."
Jersey are in their second season in the Championship - the highest level the club has ever played at - after finishing second-from-bottom of the table in the 2012-13 season to stay up.
Harvey's final game in charge proved to be a disappointing 28-18 home defeat at the hands of fellow Championship strugglers Ealing Trailfinders, who had lost all nine of their previous league fixtures.
Jersey chairman Bill Dempsey said: "We are sorry that Ben has come to this decision.
"His hard work, effort and enthusiasm has been instrumental in enabling Jersey to rise rapidly through the leagues to the level at which we now play.
"We would like to thank him for what he's done and wish him well in the future."
Forwards coach Steve Boden has been placed in interim charge of the club's playing affairs, with Jersey's next game coming in the British & Irish Cup against Cornish Pirates at the weekend.
Harvey's playing career saw him turn out for Bristol, Richmond and Worcester at fly-half as well as representing the England Sevens side.