Starting in 1972 with L. Sprague de Camp's Scribblings at Boskone 10, NESFA Press has usually published a Boskone Book by Boskone's Guest of Honor. The books are sometimes collections of stories, sometimes essays, and sometimes trunk novels.
They are always limited, numbered editions. In the early days, the books were a small size — just larger than a typical mass-market paperback — but starting with Boskone 30, the Boskone Book became a more normal size: 8.5"x5.5".
The edition is usually split with the bulk of the edition being simply numbered, while the lower numbers were in some way special. In the early days, they were "finebound" — low-numbered copies of the regular state rebound in leather. Later they were a state bound in leatherette and slipcased. The special state is always signed by the author and artist.
In recent years, having a Boskone Book at each Boskone has started to become the exception rather than the rule.