Head Shots and Composite Cards

I'm not from Chicago, but I've been in theatre since I was 13. Don't ever sign up for a company that wants money upfront. Only trust agents that make money if you do. As for headshots, a professional photographer that does headshot is your best bet.
But since i'm a starving student, is go to my local college where there is photography students and ask if any of them is willing to do things for cheap. Some of my best shots have come from a $20 session with them and I get 10x more pics to choose from than a pro.

Check for agencies in Chicago that represent children. As was stated below, if an agency asks for any money up front run away, it is a scam!
Reputable agencies will either have an open call or ask for you to send them snapshots of your child and if they like what they see they will call you in for a meeting. Get agency representation first before spending a lot of money on head shots or comp cards because they will have photographers that they recommend and will want to choose the shots they think are the best. Message me if you want any more help, our whole family is in the business.

Go to Fordmodels.com and post pictures of your child for reveiw. They can be pictures you took yourself. If they think your child has potential they will contact you. From there you will be told what pictures they need and where to have them taken. I have a friend who is an artist rep for musicians and his office is contacted often by Ford Models looking for child models. He keeps telling my kids to put up their kids pictures. Ford models has been around for many, many years and is reputable. I believe they have an office in the Chicago area.
Good luck, this could be a college fund in the making.

first of all, how old is your child. If they are under a certain age you don't need professional head shots. Baby through toddler you just take pictures to the agency specifications. The faces of young children change so rapidly that any decent angency will not have you waste your money on head shots. If they do, there's something wrong.