I have always resisted numbering my volumes; partly because, in the early days, I thought the books were distinct enough; latterly because if I ever decided to drop in a prequel somewhere (which in fact I did most lately with Captain Vorpatril’s Alliance) it would upwhack the numbering system.  Nevertheless, the books and stories do have a chronological order, if not a strict one.

It was always my intention to write each book as a stand-alone so that the reader could theoretically jump in anywhere, yes, with that book that’s in your hand right now, don’t put it back on the shelf!  While still somewhat true, as the series developed it acquired a number of sub-arcs, closely related tales that were richer for each other.  I will list the sub-arcs, and then the books, and then the caveats.

Shards of Honor and Barrayar.  The first two books in the series proper, they detail the adventures of Cordelia Naismith of Beta Colony and Aral Vorkosigan of Barrayar.  Shards was my very first novel ever; Barrayar was actually my eighth, but continues the tale the next day after the end of Shards.  For readers who want to be sure of beginning at the beginning, or who are very spoiler-sensitive, start with these two.

The Warrior’s Apprentice and The Vor Game (with, perhaps, the novella “The Mountains of Mourning” tucked in between.)  The Warrior’s Apprentice introduces the character who became the series’ linchpin, Miles Vorkosigan; the first book tells how he created a space mercenary fleet by accident; the second how he fixed his mistakes from the first round.  Space opera and military-esque adventure (and a number of other things one can best discover for oneself), The Warrior’s Apprentice makes another good place to jump into the series for readers who prefer a young male protagonist.

After that: Brothers in Arms should be read before Mirror Dance, and both, ideally, before Memory.

Komarr makes another good alternate entry point for the series, picking up Miles’s second career at its start.  It should be read before A Civil Campaign.

Borders of Infinity, a collection of three of the five currently extant novellas, makes a good Miles Vorkosigan early-adventure sampler platter, I always thought, for readers who don’t want to commit themselves to length.  (But it may make more sense if read after The Warrior’s Apprentice.)  Take care not to confuse the collection-as-a-whole with its title story, “The Borders of Infinity”.

Falling Free takes place 200 years earlier in the timeline and does not share settings or characters with the main body of the series.  Most readers recommend picking up this story later.  It should likely be read before Diplomatic Immunity, however, which revisits the “quaddies”, a bioengineered race of free fall dwellers, in Miles’s time.