The Banana Split Affair — Cynthia Blair

Susan is a shy straight-A student and talented artist. Her twin sister Christine is outgoing and popular. Envious of each other's lives, they decide to trade places.  But complications arise when Chris falls for the boy Susan likes and Susan has to hide her identity from a boy she meets.  Both girls face ups and downs as they learn about romance, each other, and themselves. Young Adult Fiction by Cynthia Blair; originally published by Fawcett Juniper