This article examines the time-dependent Hartree-Fock (TDHF) approximation of
single-particle dynamics in systems of interacting fermions. We find the TDHF
approximation to be accurate when there are sufficiently many particles and the
initial many-particle state is a Slater determinant, or any Gibbs equilibrium
state for noninteracting fermions. Assuming a bounded two-particle interaction,
we obtain a bound on the error of the TDHF approximation, valid for short
times. We further show that the error of the the TDHF approximation vanishes at
all times in the mean field limit.