The points of issue
Baen mass-market paperback original, August 1986; copyright page carries Baen's stated first-printing line (First printing, August 1986) with no later printings listed. First Miles Vorkosigan novel.
Is this the true first?
The US Baen paperback original (August 1986) is the true first; there is no earlier hardcover.
Telling it from reprints & book-club editions
The first hardcover appearance was the book club omnibus Test of Honor (Nelson Doubleday/SFBC, 1987), which pairs it with Shards of Honor; the NESFA Press hardcover is a much later edition.
Frequently asked questions
Is my copy of The Warrior's Apprentice a first edition?
Look for these first-edition points: Baen mass-market paperback original, August 1986; copyright page carries Baen's stated first-printing line (First printing, August 1986) with no later printings listed. First Miles Vorkosigan novel.
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. The US Baen paperback original (August 1986) is the true first; there is no earlier hardcover.
Is the book-club edition the same as the first?
The first hardcover appearance was the book club omnibus Test of Honor (Nelson Doubleday/SFBC, 1987), which pairs it with Shards of Honor; the NESFA Press hardcover is a much later edition.
I have a first edition of The Warrior's Apprentice — 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.