The gray titi monkey was born on Monday. The new monkey doesn't have a name yet and is one of about 50 in captivity. According to zoo officials, this is the eighth offspring for the monkey's mother and father.
This type of rare monkey mates for life and zoo officials say caring for a newborn is a family affair.
"Having a newborn in the group is a very exciting thing not just for us, but for them, too, because it's a family operation as far as raising the offspring," said Dave Bernier, Lincoln Park general curator.
The titi monkey weighs about two pounds when fully grown and it lives on fruit, leaves and insects.