Third-graders Jane-Marie and Carolyn have been best friends since preschool. But when Jane-Marie betrays her friend by telling one of her secrets, Carolyn is unforgiving. It doesn't help that Jane-Marie is also jealous because Carolyn wants to be friends with another girl, or that she calls Carolyn's secret ""dumb."" Willner-Pardo (What I'll Remember When I Am a Grownup, 1994, etc.) writes realistically in four brief chapters of the next month as the girls spend time without the other. They sit with different girls at lunch, missing each other, making new friends, and finally finding a way to get along together. Poydar's suburban scenes enhance the amiable atmosphere of this engaging and sensitive look at friendship.