Top 10 most frequently challenged books of 2013.

From the Guardian:

Captain Underpants (series), by Dav Pilkey

Reasons: Offensive language, unsuited for age group, violence

The Bluest Eye, by Toni Morrison

Reasons: Offensive language, sexually explicit, unsuited to age group, violence

The Absolutely True Diary of a Part-Time Indian, by Sherman Alexie

Reasons: Drugs/alcohol/smoking, offensive language, racism, sexually explicit, unsuited to age group

Fifty Shades of Grey, by EL James

Reasons: Nudity, offensive language, religious viewpoint, sexually explicit, unsuited to age group

The Hunger Games, by Suzanne Collins

Reasons: Religious viewpoint, unsuited to age group

A Bad Boy Can Be Good for a Girl, by Tanya Lee Stone

Reasons: Drugs/alcohol/smoking, nudity, offensive language, sexually explicit

Looking for Alaska, by John Green

Reasons: Drugs/alcohol/smoking, sexually explicit, unsuited to age group

The Perks of Being a Wallflower, by Stephen Chbosky

Reasons: drugs/alcohol/smoking, homosexuality, sexually explicit, unsuited to age group

Bless Me Ultima, by Rudolfo Anaya

Reasons: Occult/Satanism, offensive language, religious viewpoint, sexually explicit

Bone (series), by Jeff Smith

Reasons: Political viewpoint, racism, violence