  In a class of spatially homogeneous cosmologies including those of Bianchi
type I--VIII mathematical results are presented which show that a scalar field
non-minimally coupled to the scalar curvature of spacetime can dynamically
yield a positive cosmological constant without the potential being required to
include one. More precisely, it is shown that in an exponential potential any
positive coupling constant leads eventually to late-time de Sitter expansion
and isotropization corresponding to a positive cosmological constant and that
this behaviour is independent of the steepness of the potential. This is in
marked contrast to the minimally coupled case where power-law inflation occurs
at most, provided the potential is sufficiently shallow.
