I'd say ages 8 and up.

Nicholas by Goscinny and Sempe, about a naughty French school boy, it's just been printed in English and you can find it in any major bookstore.  I started reading it aloud to my 9 and 11 year olds today and even I was laughing.  Loudly!  My friend Amy (fellow book lover!) and I had seen in in Barnes and Noble a month or so ago and we thought it looked so cute, but it was quite expensive, $19.99 for a hardback childrens book that may or may not be good...well it's good and worth every penny.