  HYDRA spectra of 287 stars in the field of NGC 2506 from the turnoff through
the giant branch are analyzed. With previous data, 22 are identified as
probable binaries; 90 more are classified as potential non-members.
Spectroscopic analyses of ~60 red giants and slowly rotating turnoff stars
using line equivalent widths and a neural network approach lead to [Fe/H] =
-0.27 +/- 0.07 (s.d.) and [Fe/H] = -0.27 +/- 0.06 (s.d.), respectively. Li
abundances are derived for 145 probable single-star members, 44 being upper
limits. Among turnoff stars outside the Li-dip, A(Li) = 3.04 +/- 0.16 (s.d.),
with no trend with color, luminosity, or rotation speed. Evolving from the
turnoff across the subgiant branch, there is a well-delineated decline to A(Li)
~1.25 at the giant branch base, coupled with the rotational spindown from
between ~20 and 70 km/s to less than 20 km/s for stars entering the subgiant
branch and beyond. A(Li) remains effectively constant from the giant branch
base to the red giant clump level. A new member above the clump redefines the
path of the first-ascent red giant branch; its Li is 0.6 dex below the
first-ascent red giants. With one exception, all post-He-flash stars have upper
limits to A(Li), at or below the level of the brightest first-ascent red giant.
The patterns are in excellent qualitative agreement with the model predictions
for low/intermediate-mass stars which undergo rotation-induced mixing at the
turnoff and subgiant branch, first dredge-up, and thermohaline mixing beyond
the red giant bump.
