K.S.
I add my support for sign language for pre-verbal and early verbal kids. My son is a very strong personality with strong opinions and his frustration level was so much lower when he was able to use sign language. We concentrated on basic signs first (more, water, milk, hungry). If those go well you can always add more. My son is 3 now and highly verbal but his preschool still teaches a lot of signing and we are going to start using certain signs (like the sign for "help") with him because he is hesitant to use words in certain situations and his teacher thinks the signs will help.