New theoretical stellar models for the lower end of the main sequence have been computed for a wide range in metallicity. These models are based on new low-temperature opacities, which include the contributions from the most important molecules, as well as published model atmospheres, which guided the choice of surface boundary conditions. While the present treatment of the nonideal gas effects is only approximate, reasonable agreement is found with those models comuputed with a more sophisticated equation of state for solar-like composition. The results are compared with the available observations of late-type dwarfs on both the (M(bol), log T(eff)- and (M(bol), mass)-planes, and satisfactory agreement is found. In particular, some preliminary observational data appear to be consistent with the model prediction that the most metal-poor subdwarfs should be up to 3 mag subluminous on the theoretical H-R diagram.