"It's a little weird," said Harden, who planned to take his sister, Kristen, out for a nice dinner Saturday night. "I'm definitely excited."
He will make $500,000 this season, a hefty increase from his original contract for 2005, which called for a $336,500 salary. He will make $1 million in 2006, $2 million in 2007 and $4.5 million in 2008. The club option is for $7 million and does not include a buyout.
The deal also includes escalators based on innings pitched.
"It's nice writing his name down every fifth day," manager Ken Macha said. "It's a tribute to the development he's made. I think his progress has been a steep upward curve. I'm sure this will put a smile on his face."
Harden will be happier once he's on the mound Wednesday in Baltimore. He has a blister on the middle finger of his pitching hand that kept him from making an exhibition start Friday against the San Francisco Giants. He is scheduled to throw a side Monday and then the team has an off day Tuesday, which could allow the A's to alter their rotation if Harden isn't ready.
"I'm definitely optimistic," he said. "I'm pretty certain about it."
Assistant general manager David Forst, who handled the bulk of the negotiations, compared the contract to the deals Hudson, Mulder and Barry Zito received at similar stages of their careers.
"It's exciting to know I'm kind of in the same category as those guys," Harden said. "I don't think I could be happier. This is a team I want to play for the next four or five years."
Harden, 23, enters his third major-league season after an impressive second half last year. He went 11-7 in 2004, including 8-2 with a 3.49 ERA in 15 starts after the All-Star break.
Talk of a new contract for Harden began at the beginning of spring training, with the aim of having something done by Opening Day.
"Rich and his family were very aware this was about the same time we talked to Hudson, Mulder and Zito," Forst said before the A's hosted the Giants. "It made sense from our standpoint. It was easy to line him up with those guys at this point in his career.
"He's matured over the past two years from the time he first was here," Forst said. "He's a young kid with fantastic stuff. The progress we've seen and the track record he had the second half last year, at least from the way we project him, he's going to be one of the top pitchers in the American League, if he's not already."
This was the first signing since the A's changed ownership. Los Angeles real estate developer Lewis Wolff finalized the purchase of the team Thursday from Steve Schott and Ken Hofmann.
"The new ownership group was willing to work with us," Forst said. "They're learning the process just like they are everything else. As soon as we presented this to Lew, he was on board and wanted to get it done."
The A's have had initial conversations with the representative for shortstop Bobby Crosby, the AL rookie of the year, about a similar deal.