S.C.
It was the hardest thing I ever did, but I let them cry it out. I did this with my first child at 4 months and she has always been a good sleeper. I waited a little longer with the 2nd- we're just starting it now and she's 1. The first night was the worst. She cried for over 30 minutes- hysterically. Then it got to be shorter and shorter. After a few days they would cry a few minutes and fall asleep. Finally they would quietly go to sleep without any fuss at all. This also makes a big difference in night time wakings. They calm themselves down with out you having to come rock them to sleep again. Good luck!