Raised by humans since she was six months old, Koko was the first gorilla taught to "talk" using American Sign Language. Scientist Penny Pattersons's history of teaching ASL to Koko and general information about gorilla behavior are interspersed with lively anecdotes of Koko's interactions with the author during her visit with the gorilla. Koko is presented with respect and integrity, and a brief afterword discusses the human threat to gorilla habitats in Africa. Softly shaded, large illustrations are generously scattered throughout the text. (Ages 8-10)