The law also gives nursing mothers the right to go to court against any agency or business that tries to stop them from breastfeeding. It goes into effect immediately.
The measure was prompted by a woman from the Chicago suburb of LaGrange. Kasey Madden launched a campaign after being chastised by a health club manager for nursing her baby in the gym's day care area.
Sen. Don Harmon of Oak Park was one of the bill's sponsors. He says Illinois now joins 25 other states in declaring that women have the right to breast-feed their babies.