The points of issue
Baen hardcover; copyright page states 'First printing, May 2002' (Baen states first printing with month and year rather than 'First Edition'), with full number line ending in 1; priced jacket.
Is this the true first?
US Baen hardcover (May 2002) is the true first.
Telling it from reprints & book-club editions
SFBC edition exists.
Frequently asked questions
Is my copy of Diplomatic Immunity a first edition?
Look for these first-edition points: Baen hardcover; copyright page states 'First printing, May 2002' (Baen states first printing with month and year rather than 'First Edition'), with full number line ending in 1; priced jacket.
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 Baen hardcover (May 2002) is the true first.
Is the book-club edition the same as the first?
SFBC edition exists.
I have a first edition of Diplomatic Immunity — 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.