The points of issue
First edition 1971, Atheneum (New York), stated 'First Edition' on the copyright page with no later-printing line. Grey cloth with a purple mouse to the front board and purple spine lettering; in-text and full-page illustrations by Zena Bernstein. First-state jacket retains the original printed price on the front flap and does NOT bear the Newbery Medal seal.
Is this the true first?
US Atheneum 1971 is the true first. Winner of the 1972 Newbery Medal. O'Brien (pseudonym of Robert Leslie Conly) died in 1973, so signed copies are scarce.
Telling it from reprints & book-club editions
Book-club editions add the Newbery seal, are unpriced, and may carry a blind-stamp; common as later reprints.
Frequently asked questions
Is my copy of Mrs. Frisby and the Rats of NIMH a first edition?
Look for these first-edition points: First edition 1971, Atheneum (New York), stated 'First Edition' on the copyright page with no later-printing line. Grey cloth with a purple mouse to the front board and purple spine lettering; in-text and full-page illustrations by Zena Bernstein. First-state jacket retains the original printed price on the front flap and does NOT bear the Newbery Medal seal.
How do I tell the first printing from a later one?
Check the copyright page for the publisher's first-printing convention and confirm the points above. US Atheneum 1971 is the true first. Winner of the 1972 Newbery Medal. O'Brien (pseudonym of Robert Leslie Conly) died in 1973, so signed copies are scarce.
Is the book-club edition the same as the first?
Book-club editions add the Newbery seal, are unpriced, and may carry a blind-stamp; common as later reprints.
I have a first edition of Mrs. Frisby and the Rats of NIMH — what should I do?
If you're clearing books, New Mexico Literacy Project offers free pickup in Albuquerque, any condition, and makes sure collectible copies aren't lost. To sell, see the author's collecting guide. Either way, nothing valuable ends up in a landfill.