We , the Morris-butler House (Indianapolis, IN), were just talking about this the other day.  Yes indeed a young girl of 13 would be in a corset. It would not be as severely shaped as the adult ones.  Younger children were also put in corsets to learn proper posture too, but again they were shaped differently.   
I took a look around and I could not find my documentation tonight, if you really want it, I can get it for you. 

-Alice Smith-Goeke
Museum Studies Grad student, IUPUI

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Date:    Mon, 21 Jan 2008 08:43:38 -0500
From:    SBC Museum <[log in to unmask]>
Subject: Corset Question


Hello all-- I am sure there is someone on the list who can offer 
assistance with this question: at approximately what age did girls in 
the late 19th century put on their corsets? I am working with my theater 
department on a short program featuring the character of a girl who 
would have been 13 in 1882. They want to know if she would have been 
wearing a corset under her costume--and I have no idea! Would it depend 
on whether she needed it or not, or were they traditionally worn when 
girls reached a certain age? Thank you in advance for any assistance!
-- Christian Carr Director, Sweet Briar Museum Assistant Professor of 
Arts Management PO Box 144, Sweet Briar, VA 24595 Phone: 434.381.6246 
Fax: 434.381.6132 (mailing address same as above)

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