Cool Stars 14 - Submitted Abstract # 376 This version created on 05 October 2006 Low mass, low metallicity stellar evolution models computed with a non-grey surface boundary condition Gregory J. Harris, University College London Anthony Lynas-Gray, University of Oxford Steve Miller, University College London Jonathan Tennyson, University College London It has been shown (Saumon & co-workers) that, the grey approximation provides a poor surface boundary condition for stellar evolution models of cool dwarf stars. We discuss preliminary results of hydrogen burning stellar evolution calculations for low mass low metallicity stars. These calculations show that the grey approximation results in an over prediction of effective temperature on the red giant branch. ----------------------------------