  We make use of the Next Generation model atmospheres by Allard et al. (1997)
and Hauschildt, Allard & Baron (1999) to compute theoretical models for low and
very low-mass stars for selected metallicities in the range Z= 0.0002 to 0.002.
On this basis, we present theoretical predictions covering the sequence of
H-burning stars as observed in galactic globulars from the faint end of the
Main Sequence up to, and beyond, the cluster Turn Off. The role played by the
new model atmospheres is discussed, showing that present models appear in
excellent agreement with models by Baraffe et al. (1997) as computed on quite
similar physical basis. One finds that the theoretical mass-luminosity
relations based on this updated set of models, are in good agreement with the
empirical data provided by Henry & McCarthy (1993). Comparison with HST
observation discloses that the location in the Color-Magnitude diagram of the
lower Main Sequence in galactic globular clusters appears again in good
agreement with the predicted sensitive dependence of these sequences on the
cluster metallicity.
