  We consider models where moduli fields are not stabilized and play the role
of quintessence. In order to evade gravitational tests, we investigate the
possibility that moduli behave as chameleon fields. We find that, for realistic
moduli superpotentials, the chameleon effect is not strong enough, implying
that moduli quintessence models are gravitationally ruled out. More generally,
we state a no-go theorem for quintessence in supergravity whereby models either
behave like a pure cosmological constant or violate gravitational tests
