This seems to be getting lots of attention, so here are my views. Let me start by saying, each baby is different and the first year is the most difficult. For our first daughter, we were novice parents. So, we just held her. We rocked her. I nursed her. Whatever it took to get her to close her eyes and sleep, we did. I mean, come on, all the story books and lullabies you see the Mom or Dad rocking the baby to sleep. Isn't that why the rocking chair was invented? This worked...for a while.
Then at around 6 weeks, she started to wake up during the day and could not fall back asleep unless she was carried, in a carseat, or a swing. What had happened to our sleepy baby? Whenever I tried putting her down during the day after she had fallen asleep, she would wake up in 5-10 minutes, crying yet again. What was going on?
With our trip to the pediatrician, she recommended Weissbluth's book and then I realized what we were doing wrong. We were not teaching our baby how to fall asleep on her own. What a concept. I never thought that would be such a challenge, to fall asleep! So, little by little, we let her cry before naptime or g'night time. Sometimes, she cried a lot. Sometimes, it was heartbreaking. But after we started the new 7-7 schedule and appropriate nap time (see Sleeping Babies, Healthy Babies), she was more content. less tired, and better at falling asleep on her own.
With our second child, we started the schedule and learning to sleep on her own from day one. I would sing her "Somewhere over the rainbow," dance with her a bit and put her in her pack-n-play bassinet. She would be drowsy, but awake and she would look at her Piggy and close her eyes. It was lovely. However, she did go through a month (at about 3 months) where she cried for about 45 minutes before she settled down and fell sleep for the night. It was during those nights, I would close her door and go out for an hour to buy groceries while Papa stayed and watched sports in the other room. However, after the 3-4 weeks, she fell asleep with no problem.
She is our child that can sleep anywhere, anytime. I once had to pick up M from school and it was snowing. I had H on the sled, and I looked back to see she had fallen asleep...sledding. All the way to school and all the way back. She has fallen asleep on the floor in the living room. She can sleep through when I take her to pee-pee at night before I turn in. She is my sleeping champ.
That's our baby sleep story. Hope this helps somebody. I have consulted many Moms about this topic - it has individual hiccups along the way, but it almost inevitably ends up Mom or Dad adopting these sleep strategies.
Why the pack-n-play and not a crib? That can be for another entry.