The dispersion and settling of small, heavy, spherical particles in a temporally evolving two‐dimensional mixing layer under gravity is investigated. The dilute limit is assumed, in which both the effect of the particles on the fluid flow and the interaction among the particles is negligible. The particle dynamics is quantified as a function of the dimensionless Stokes and Froude numbers, St and Fr, which express the ratios of the three time scales related to (i) the fluid flow, (ii) the particles’ inertia, and (iii) their settling velocity, respectively. For horizontal flow in which the upper stream is the seeded one, the mixing layer accelerates the settling of particles with small St, whereas particles with large St are slowed down in their settling motion. At intermediate St and for moderate settling velocities, root‐mean‐square (RMS) data for the particle concentration field demonstrate the generation of strong inhomogeneities by the mixing layer. These regions of high particle concentration have the form of bands in the initially unseeded stream. Scaling laws for their angles and the distance between them are given. Furthermore, analytical results for linearized flow fields are derived that demonstrate the optimal efficiency of the dispersion and settling process at intermediate St. The numerical simulations show the existence of different parameter regimes, in which the particle motion is dominated by the coherent vortices and by gravity, respectively. Scaling laws are derived for the particle dispersion and settling for both of these regimes, which show reasonable quantitative agreement with the simulation data. Flows that exhibit a vortex pairing process show a reduced tendency of the particles toward suspension. For vertically upward flow in which the faster stream is seeded, is observed a sharp maximum in the particle dispersion measures for intermediate St and settling velocities equal to one‐half the difference between the free‐stream velocities. Under these conditions, the cross‐stream fluid velocity components become optimally efficient in ejecting particles into the unseeded stream. ©1995 American Institute of Physics.