Links for Free Admission to Chicago Museums

These links go right to the free date sites:
Free Days at the Shedd
Museum of Science and Industry Free Days
Free Days at Adler Planetarium
Field Museum Free Days (second Tuesdays are free, other dates are also listed here)

These locations have regular free days, so I've linked to their home pages:
Chicago History Museum Free Days (every Monday)
Art Institute of Chicago (Thursday nights, 5-8 PM)
Brookfield Zoo (free days during the winter--January & February)
Chicago Children's Museum (Thursday nights, 5-8 PM)
Lincoln Park Zoo (every single day, all year)
Museum of Contemporary Art (every Tuesday)
Notebaert Nature Museum (Thursdays are "suggested donation" days)