We use a generalized van der Waals molecular theory to study a model substr
ate-nematic interface in the regime of complete wetting and in a situation
of competing interactions at the interface. The analysis shows that an anch
oring transition between states with planar and homeotropic director config
uration may play the role of a prewetting transition, and that reentrant an
choring must generally occur. As a result one expects complete wetting in a
finite temperature range. The study provides a general context within whic
h anchoring and wetting phenomena can be related. [S0031-9007(99)08841-9].