There was a theory in the 1970's based on the work of Doman-Delacatto that crawling is necessary for optimum brain development. I don't know if that research still stands. What I do know is that many babies don't crawl and they go on to lead perfectly normal lives! I don't advise worrying about this. However, if you do want to worry anyways, then there is something you can do with your youngster that may make up for the crawling deficit: an activity called "brain gym." You can find information about this on-line. In addition, giving your toddler some gym and/or sports classes appropriate for his age group can certainly help wire the brain as well.   Sarah Chana