A conditional mean-field approach to strongly chaotic coupled map latt
ices is presented. Tt focusses on the time evolution of the one-body p
robability distribution function p(X) of instantaneous site values. Th
e local environment of a site is modelled in terms of an effective num
ber of independent neighbours, while keeping the Perron-Frobenius oper
ator to account for the action of the local map. This approximation is
shown to produce distributions p(X) in agreement with empirical obser
vations of non-trivial collective behaviour, and captures the essence
of their dynamics.