A numerical study of buoyancy-driven transport from an isothermal symmetrically heated L-shaped corner is reported. The effect of the length of the heated horizontal surface on heat transfer from the vertical surface and the concomitant complex changes in the entrainment flow characteristics are discussed. Results are reported for a wide range of Rayleigh number. The unsteady laminar flows at high Rayleigh numbers exhibit interesting interactions between the horizontal and vertical entrainment flows. Their transient behavior is investigated in detail. The effect of Prandtl number, independent of Rayleigh number, is shown to be significant. In the lower Rayleigh number range, the Nusselt number for each surface of the L-corner is compared with the Nusselt number for the corresponding single surface. The underlying basic physical processes are discussed. Steady and transient Nusselt number data are provided.