HB - School Library Journal
Oppel has taken a fascinating subject and molded it into a top-notch read. Deftly integrating family dynamics, animal-rights issues, and the painful lessons of growing up, Half Brother draws readers in from the beginning and doesn't let go. The carefully crafted characters will be an easy connection for teens and the interpretation of the animal-testing controversies of the 1970s will provide an alternate viewpoint for animal-book lovers.
– School Library Journal (starred review)