Fluorescence depolarization studies  offer a powerful way of obtaining
information on the static and dynamic properties of molecules dissolved
in liquid crystals and other anisotropic fluids. In this talk two
types of such studies will be discussed.
The first is the case of rotational depolarization for probe molecules dissolved in low viscosity liquid crystals and we shall see how uniaxial and biaxial order parameters as well as information of the full rotational diffusion tensor can be obtained for different solutes, even as complex as chlorophyll a in a nematic .
We shall then consider the case of depolarization through Förster type energy transfer in ordered systems, which allows obtaining structural information even in systems so viscous that rotational depolarization does not effectively occur. We shall discuss in particular an approach that we have recently proposed that couples computer simulations to obtain equilibrium configurations for the system and a stochastic approach for the energy transfer and that we have used to investigate how the molecular organization of the phase and its changes from isotropic to nematic and smectic or respectively from isotropic to columnar affect the features of the energy transfer and its directionality.