The dynamics of unconfined, spatially developing shear layers is studied through the numerical solutions of the time-dependent Euler equations using a second-order Godunov scheme. The effects of density and velocity variations between the two streams of the shear layer are studied and color graphics are used to show more clearly the entrainment process of the surrounding streams. The calculations demonstrate that the evolution of the mean flow is dominated by two-dimensional, inviscid effects. The r.m.s. fluctuating velocity and density profiles are in good agreement with the measurements of Oster and Wygnanskiand of Konrad, except for the peak value of thev′ profile.