Financial terms weren't released.
The Eagles traded up two spots to select Maclin with the 19th pick in the NFL draft. Maclin caught 102 passes for 1,260 yards and 13 touchdowns as a sophomore at Missouri last season.
Earlier in the day, quarterback Donovan McNabb downplayed Maclin's absence and cautioned against expecting too much from him.
"He's a rookie. You all act like he's been in the league for five or six years," McNabb said. "You don't know what he's going to do anyway. All we ask of him is to catch the ball and get up field and score. That's all we ask. He's a receiver."
Maclin caught 80 passes for 1,055 yards and nine TDs his freshman year. He also ran the ball quite a bit, finishing with 91 carries for 668 yards and six TDs on the ground. Maclin returned three punts and two kickoffs for scores in his two seasons.
It's likely he could end up making a bigger contribution on special teams, especially early in the season.
"I thought he did a good job this spring in the OTAs," special teams coordinator Ted Daisher said Sunday. "He's making progress. He's gotten better. That contract thing will work itself out and when it does he'll be here. We'll just coach him up. The other guys are doing a good job."
Maclin was the first receiver selected by the Eagles in the first round since they took Freddie Mitchell in 2001 at No. 25. Mitchell was a bust in Philadelphia.