It has been a full couple of days of “Who wrote X”-type questions. Most recently, Who wrote Go Ask Alice?
An interesting question. The cover of the book–in every version I’ve ever personally laid eyes on–says “by Anonymous.”
The Library of Congress catalog also lists Anonymous.
But Worldcat.org lists Beatrice Sparks as the author. As soon as I saw that, I knew it was probably true. I knew that Sparks had written the book Jay’s Journal, which has a similar feel and also credits “anonymous” on the cover of the copy I own.
So we’ll go with Beatrice Sparks.