I did a search and found no mention of counting at 3 but counting to 4 at age four was expected, so it seems your child is learning at a normal rate. I would mention it to the ped to be sure but also keep in mind that kids tend to learn things at their own pace, when they are ready. While my child is the opposite of yours, in that he tends to learn things early and fast (so you may want to take my words with a grain of salt as I have not walked in your shoes) he still has to be ready. There are things I thought he was ready and capable of and keep encouraging, like reading. He knew all his letters and the sounds associated with them and that letters went together to make words but he would not read for month after having this knowledge and ability. He still insists he can not read book even though he can sound out words very well. For whatever reason he does not feel ready and we respect that while gently encouraging. He would also not try to write letters and numbers for ages(and he would not be expected to developmentally but since he tends to be fast on other things I found myself looking for this skill as well) or even draw anything more then a circle or a quick scribble for ages, then suddenly, around 3.5, he was fasinated with these things and doing them frequenty without encouragement. I don't remember when my son learned to count to 3 but I have definately heard moms comment that kids seem to stop at some number for the longest time somehow unable to take the concept of numbers further and than suddenly they are ready and jump to count another 10 numbers. While I would tend to expect a 3 year old to count beyond 3 in a quick search of milestones the first place I saw any counting expectation was at age 5, though by then they indicated child usually can count to 10.