  It is currently accepted that Hot-Bottom-Burning (HBB) in intermediate-mass
asymptotic giant branch (AGB) stars prevents the formation of C~stars.
Nevertheless, we present in this paper the results of some detailed
evolutionary calculations which show that even with HBB we obtain C~stars at
the highest luminosities reached on the AGB. This is due to mass-loss reducing
the envelope mass so that HBB ceases but dredge-up continues. The high
mass-loss rate produces an optically thick wind before the star reaches C/O>1.
This is consistent with the recent results of van Loon et al. (1997a,b) who
find obscured C~stars in the Magellanic Clouds at luminosities up to M_{bol} =
-6.8.
