This subject is in hot debate. Rather than focusing on whether to let babies cry it out or not, I decided to focus on how to get kids to sleep well. There are MANY, MANY theories and opinions about what helps a child sleep.
I have researched many articles and ideas about this issue over the past month. I have heard opinions from every day moms (friends at playgroups), well known doctors (Dr. Sears) and authors of the best sleep books (see below). What many of these experts agree is this:
Babies do not sleep like adults. They generally sleep in increments and wake up for reasons related to discomfort, hunger or their own temprament. There are many things you can do to help babies to sleep better but it's unrealistic to expect it consistantly.
When a baby is 0-3 months it's believed that getting babies to start distinguishing day from night can be helpful. Keep the lights off, voices quiet and stimulation to a minimum during nighttime hours. Between 3-5 months babies are often ready for a schedule in which having a bedtime routine such as bath, book, and rocking is thought to be helpful by many parents. Talk to your doctor about feeding schedules, teething and what is best for you and your child. You can also access online resources such as http://www.babywhisperer.com/ and http://www.babycenter.com/. Go onto the message boards on these sites where you can look at what other parents have written for babies your child's age. I thought this was helpful with my daughter so I could get an idea of what was reasonable to expect and what other moms were doing.
Don't expect to ALWAYS know what your child needs. I know how you feel. It feels like you should always be able to soothe your child since you're their mother. That is unrealistic for you and for your baby. Your baby will need to learn self soothing techniques which is a natural part of the human psyche. Pacifiers and thumb sucking can be helpful for a baby to sooth themselves back to sleep. Also, music and white noise machines can imitate the sounds of the womb and be soothing. There are times when these things don't work and you are at your wits end.
Should you let your child cry it out? This approach is also known as the Ferber method. It is a method in which you should let your child cry until they fall asleep. There is research to support both sides of this issue. I am a big believer that a mother should follow her intuition and do what she feels is best (although neither feels good at the time!) What works for one parent might not work for another parent and what worked for one child might not work for the next child. Whatever you decide, remember that babies are extremely resilient and will not be traumatized by your decision. If one method isn't working, try something else. Try to be patient, as the saying goes, "this too shall pass".
Helpful books: Healthy Sleep habits, happy child by Marc Weissbluth, Nighttime Parenting by Dr. Sears
Other helpful resources: Your pediatrician and other moms. Join a moms group for support.