A new category of books has emerged from the abundance of Young Adult titles that has many people confused. New Adult is the term applied to books that feature characters who are no longer in high school but are not considered full adults. Generally, these books cover the college years and follow characters in their late-teens and/or early-twenties, ages 18-25.
Parents should be aware that books labeled New Adult may contain more frequent and more explicit sexual material. Additionally, characters often consume alcohol regardless if they are of legal age. There is a general lack of parental involvement as the characters in New Adult have moved away from home or are in process of becoming independent members of society, separate from the family that raised them.
Generally, New Adult books would be appropriate for older high school students – ages 16+ – and college-aged young adults.
If you would like to read more about the New Adult classification, please check out the entry in Wikipedia. Another good article can be found at USA Today.