When should my baby be able to roll over?
The general rule of thumb is that babies will roll from belly to back first, at about 4 months of age. Then they roll from back to stomach a little later, but usually by 6 months.
That said, because pediatricians began to advise parents to put babies to sleep on their backs (which has dramatically reduced the incidence of sudden infant death syndrome), we have noticed that babies don't roll over as early as they used to. Although the belly-to-back movement is easier (they can their use the arms to push over), many roll over from back to belly first now. However, because that is a more difficult achievement, it may occur later than it used to.
One thing you can do to promote rolling over is to give your baby tummy time during the day while she is awake and playing under your observation. If you're concerned you should have her pediatrician examine her carefully and follow up to make sure this milestone is achieved.