Size effects at initial yield (prior to Stage II) of micron sized specimens are modeled within a continuum model of plasticity. Two different aspects are considered here: a) specification of a density of dislocation sources that represent the emission of dislocation dipoles, and b) the presence of an initial, spatially inhomogeneous excess dislocation (ED) content. Discreteness of the source distribution appears to lead to a stochastic response in stress-strain curves, with the stochasticity diminishing as the number of sources increases.