President of baseball operations Theo Epstein said the Cubs will carry three catchers as Contreras, 24, joins Miguel Montero, 32, and David Ross, 39, who will help in the tutoring. Tim Federowicz was designated for assignment to make room for Contreras on the roster.
"We've had good experience in the past calling up young guys to get them acclimated before they have to carry a large responsibility," Epstein said. "The timing is right [for Contreras] with the team playing well and a little bit of roster flexibility.
"Most important," Epstein said, "he's earned his way up here."
On Friday, Contreras shadowed pitching coach Chris Bosio during early side work, and helped out by catching John Lackey. While at Iowa, Contreras was watching Cubs games on television, and charting the pitchers. Chicago catching coach Mike Borzello stayed in touch via text messages, telling him things to work on and watch.
"I put myself behind the plate during those games," Contreras said. "Now I'm here, and I can't wait to be on the field and be behind the plate."
How long will Contreras stay? That's still to be determined.
"It could be short [term], it could be long, it could be we need a roster spot and he has to go back," Maddon said. "What we do know is we thought to get his clock running now, he's going to help us at some point this year and maybe very dynamically by the end of the year, so right now was the right time to get this thing flowing."
Contreras, well aware of his role, soaked it all in.
"I did it -- this is what I dreamed about since I was a kid," Contreras said. "This is an amazing feeling."
"He's got everything it takes to be a big league catcher and a future All-Star catcher," Montero said.
But Montero knows that Contreras needs game experience.
"When you watch, it's one thing, and when you're behind the plate, it's another thing," Montero said. "He'll learn. He obviously has a good pitching staff to work with, which is a plus for a young guy.
"Catching these guys, everybody's different, so you have to know every single guy and what they like to do in different counts -- two strikes, whatever. That was the hardest part for me."
Maddon was impressed with Contreras' approach during Spring Training.
"He's an intense young man," Maddon said. "The biggest thing is to have him generate or process that passion he has in the right direction. He's involved every moment."