 
    
    
         
PAUL A. CROWTHER 
 Abstract
We discuss recent analyses of luminous, post-main sequence, emission
line stars based on stratified, extended non-LTE atmospheric models. 
We will address our knowledge of such objects, focusing in particular 
on Wolf-Rayet stars, LBVs, Of/WN stars, Of supergiants, and low mass
[WC] central stars of Planetary Nebulae. Derived stellar wind properties 
and chemistries are discussed, which allow the exact evolutionary sequences 
followed by the most massive stars to be identified, revealing limitations
of the standard evolutionary theory. We also discuss future requirements 
of the Standard Model, including line blanketing and clumping.
 
 Dept. of Physics & Astronomy, University College London
 
 Gower Street, London, WC1E 6BT, England