L.W.
I guess it would depend on her age. I think by 3-4 they should break the habit, but my daughter was about 7. She really only sucked it during down time like while watching TV or at bedtime. I just remember the dr. saying not to force her, as she might feel the need to hide it from me. I never got mad or made a real big deal about it, but I did try to redirect her. We tried lotion & socks on her hands. I even thought that having pretty nails would work, but she would ask me not to paint her thumb. I thought it was so cute as a baby & awesome that she could comfort herself. It's not like a pacifier that you can just hide or throw away, but as with all phases of our children's lives, it too will pass. Good luck.