It happened around 10:30 p.m. Saturday at Diamond and North Randolph streets.
Police say the baby, between 4 and 6 months old, was shot in the right armpit.
Authorities say the child was being held by his mother when two people began shooting at one another.
The toddler was taken to Episcopal Hospital in critical but stable condition.
One of the men involved in the shooting was also hit, but suffered non-life threatening wounds.
One person has been arrested for the shooting.
