Louise Fitzhugh

Harriet M. Welsch is a spy. She's staked out a spy route, and she writes down everything about everyone she sees -- including her classmates and her best friends -- in her notebook. Then Harriet loses track of her notebook, and it ends up in the wrong hands. Before Harriet can stop them, her friends have read the always truthful, sometimes awful things she's written about each of them. Will Harriet find a way to put her life and her friendships back...

When his grandfather dies, eleven-year-old Sport worries that he will be forced to live with his wealthy and greedy mother rather than remain with his kind father and new stepmother.

This special 50th Anniversary Edition of the classic and ground-breaking coming-of-age novel, Harriet the Spy, includes tributes by Judy Blume, Meg Cabot, Lois Lowry, Rebecca Stead, and many more, as well as a map of Harriet's New York City neighborhood and spy route and original author/editor correspondence.
Using her keen observation skills, 11-year-old Harriet M. Welsch writes down in her notebook what she considers the truth

...

In the world of children's literature, Louise Fitzhugh's Harriet the Spy and The Long Secret are widely recognized as epoch-making. They have been received by young readers, year after year, with excitement and love. Nobody's Family is Going to Change-the story of an African American family in New York in the 1970s-shares the vigorous sense of comedy and unflinching fidelity to the real world that has made Fitzhugh's other books into classics.