Steve McClaren has returned to Derby as the club's new manager, the Rams have confirmed.
The former England boss has made his comeback to the iPro Stadium 17 months after leaving and has signed a deal until 2018.
McClaren has replaced Nigel Pearson after he left last week following a suspension and club investigation into his conduct last month.
"I am excited to be back at Derby County as the club's manager," he told the club's official site.
"I have a great affiliation with the club, having been here on three previous occasions, and I am really delighted at the prospect of finishing what we started back in September 2013.
"I regret how my time at Derby ended back in 2015 and I am very motivated to put things right for the club and our supporters.
"My ultimate aspiration remains exactly what it was before, to take Derby County back to the Premier League."
Chris Powell had been in caretaker charge and had been tipped to get the job before McClaren emerged as a candidate on Wednesday.
Powell will remain as assistant manager with first-team coach Kevin Phillips and goalkeeping coach Pascal Zuberbuhler also staying at the club.
McClaren was sacked by Derby after two years in charge in May 2015 and took over at Newcastle the following month.
He moved to St James' Park after the Rams missed out on the Sky Bet Championship play-offs in 2014-15. Derby won just two of their last 13 games as they dropped from top to eighth.
McClaren fared little better at Newcastle and heavy spending failed to address the inadequacies in his squad before he was sacked in March with the Magpies on the brink of relegation from the Premier League.
He lost 18 of his 31 games in the north east, winning just seven.
Ex-Rams boss Pearson was appointed on a three-year deal in the summer after Darren Wassall took caretaker charge in the second half of last season when Paul Clement was dismissed in February.
The former Leicester manager won just three of his 14 games and Derby are 20th in the Championship, two points above the relegation zone, ahead of the visit of Leeds on Saturday.
Derby president and chief executive Sam Rush added: "Steve's time at Derby came to a premature end and I know he regrets that greatly. He values hugely his relationship with our supporters and I know that he will work very hard to ensure that the special connection returns."