Like the other girls have said the not crawling or walking isn't in itsself a concern but if he hasn't make any other efforts to move around then it probably would be better to get it checked out. If there is nothing to be concerned about then her mind is at ease and if there is cause for concern then its being dealt with nice and early. I found Gymbaroo really good for my little man and it also showed me games and exercises I could do with him to help develop the what I think is called parallel movement which helps their crawling and I guess ultimately walking.