I have been reading this series since I was eleven, and I have always found these books really interesting to read and analyze. However, when I introduced my brother, nine, to this series, he got emotional at a famine scene (which aren't uncommon). He never continued the series. Also, there are some themes and significant events in the series that have lots of meaning and depth, such as SPOILERS: Hollyleaf's insanity, Clear Sky's development, the reasons behind Ashfur's actions, etc. I feel younger children won't be able to appreciate the significance of these events. They might not be able to handle the violence, which there is plenty of. There are even some disturbing scenes, such as when a dying mother disowns her own son, leaving him heartbroken about the actions he committed in the past, an antagonist bleeding to death nine times over, a character getting mauled by dogs, (many) grieving scenes, and a pregnant character being kidnapped by slightly perverted tomcats (who go on to lick her cheek), etc. There are plenty more. The series also deals with racism, religious beliefs clashing, and romance. The characters are mostly good role models, but they do make some mistakes. One protagonist runs away with her forbidden mate, and gets herself pregnant. There is nothing explicit though, at least along that line. Another character rejects his son, who was still a kitten at the time. However, they (sort of) reconcile later in the series. There are many, many, characters, so that may be confusing for young kids. Also, there are plenty of inconsistencies in the books, mostly involving looks, but also involving stuff such as timeline inconsistencies, identity inconsistencies, personality inconsistencies, and plotline inconsistencies. For example, Moth Flight's Vision, the (currently) most recent book, kind of forgot about Clear Sky's redemption, and turned him from an anti-hero back to an anti-villain. That's the one thing about this series that I don't like. It can also be annoying when they kill off background characters during various timeskips, and no one ever remembers them again. (Examplecat died from illness a few months ago, the end). Otherwise, this is a great series, and I highly recommend it to tweens who can handle it.