I agree wit h the previous posts that there is a wide range of development timing. My son and I are in an early childhood family education class and there is a little boy in there who sounds alot like your grandaughter. When he was a year old he was barely sitting up and not crawling. Now at 14 months he is starting to walk. It appears he is going to skip the crawling stage entirely. He was a very crabby guy until just recently. As mentioned in the earlier post, I think that is pretty common if their intellectual and social development is more advanced than their physical. It would't surprise me if the poor thing is frustrated to death at not being able to do what she wants from a moving standpoint. Another child in the class, a girl, also was not crawling at a year. Has your daughter discussed Jessica's development with her ped. just to rule out any physical issues? If so, I would just try to fill her needs for attention as much as possible ( I realize that is a parenting style -but it did work well with my very needy son)