UPDATE: According to her family, 15-year-old Brittany Middleton has been found, and is safe.  In a Facebook posting, Brittany's mother Brandy Werczynski writes:

"Just want to thank all of you who reached out to my family with prayers and helping to get the word out about Brittany missing.  Brittany has been found safe.  We couldn't have done it without your help and prayers.  God bless you all and thank you."

The original story follows:

According to Facebook posts by her family, 15-year-old Brittany Nicole Middleton has been missing since November 25, when she was last seen in Casper with two of her friends.

Brittany is approximately 5' 2" - 5' 3", with brown hair and hazel eyes, weighs approximately 105 pounds, and is a student at Kelly Walsh High School.  If you've seen her, or have any information on her whereabouts, you're asked to call the Casper Police Department, or her mother, Brandy Werczynski, at 307-299-9394.