We consider the use in quantum Monte Carlo (QMC) of two types of valence bond wave functions based on strictly localized active orbitals, namely valence-bond self-consistent-field (VBSCF) and breathing-orbital valence-bond (BOVB) wave functions. Complemented by a Jastrow factor, these Jastrow-Valence-Bond wave functions are tested on the four diatomic molecules C2, N2, O2, and F2 in both variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC). We show that it is possible to design compact wave functions based on chemical grounds that are capable of adequately describing both static and dynamic electron correlation, and which yield accurate equilibrium well depths in DMC.