It happened around midnight Saturday night at Diversey and Kolmar.
Twenty-six-year-old Catherine Caldwell was hit by a car while rollerblading with her boyfriend.
The car didn't stop, but a witness was able to write down the license plate number.
"I really wish the person would come forth and turn themselves in," said the victim's father, Timothy Caldwell. "You really don't realize what torment and what the family is going through because of your actions."
Katie Caldwell is in critical, but stable, condition.
She suffered a concussion, a broken shoulder and a broken leg.