The Captain Underpants books are full of bathroom humor, bad jokes/puns and everything just on the nice side of gross that so many kiddos (mine are boys) can love. The books are not exactly 'nice' for those of more tender sensibilities but there are two redeeming features that are huge.First, for that reluctant reader, the books are tremendously appealing in that the kids are quite (correctly) certain that this is just for them--as though they are getting away with reading something, well, too cool for the grownups. Plus the illustrations are funny, and there are the occasional directives to the reader to go do something silly that are strangely attractive.Second, the Lexile scores are surprisingly high. I would have not expected this, but the score for the Revolting Revenge is 890. The entire series ranges from 640-890 with all but two in the 700s and 800s. This makes ME feel like I'M getting away with something, it's like sneaking ground up cauliflower into the macaroni and cheese--it's a silly book but hey, it's good for him.Fair warning, though engrossing, the books are not good for quiet time! Things like 2 page 'flip stories' heralded by the loud flap-flap-flap coming from the direction of the offspring, or the sudden outburst of a dubious song are quite startling. Perhaps right in line with a grade schooler's sense of humor, but not with a parent's (or teacher's) sense of propriety in a situation that calls for peace and quiet.My son's reluctant days of reading are far behind now, he's more like an avid reader now. However, he still loves the Captain Underpants books and informed me that CUATRROFRR-B was a Must Buy, and after reading it declared it quite entertaining. He does note that the books do not need to be read in order, but it's better if you do.Highly Recommended (by my children...and me)JTG