Wish I'd Known: Potty Training and Regression

When I was potty training my daughter, my mom warned me that:

Often times your child will regress after being potty trained

And what do you know....my mom was right :) When my daughter started having accidents again I had to come up with a new plan of attack.  That's when I introduced drawing faces.  Each time she'd go the the bathroom in the toilet, she got to draw a face on a piece of paper that I had hung up on the fridge.  When my husband got home, she'd get to show him her beautiful artwork.  This little change of reward seemed to do the trick.

I currently have a friend dealing with this situation with her daughter.  What are some tips you'd have for her?