Laminar mixed convection between a series of vertical parallel plates with planar heat sources has been studied numerically. A finite volume based method employing the SIMPLER algorithm was used for the numerical calculations. The numerical model was validated by comparing the numerical predictions with the experimentally measured values of streamwise velocities (Baek et al. 1990) for a single channel. Independent parameters that varied in this study include the buoyancy parameter (Gr/Re), the ratio of the wall conductivity to the fluid conductivity (K), and the ratio of the plate thickness to the channel width (W/B). The velocity profiles within the channel skewed substantially to the hot wall as Gr/Re increased and K decreased. The thermal conductivity ratio, K, and buoyancy parameter, Gr/Re, had a significant impact on local friction factor distribution. There was also a significant difference between the hot and cold surface heat fluxes at low values of K, while the heat flux distribution on both surfaces was essentially identical for K = 100. The effect of the exposed surface at the top of the plates was to reduce the wall temperatures near the vicinity of the plate tip, although heat was not removed out of the plate top nearly as effectively as at the plate bottom. An extended wake developed beyond the plate top for asymmetric heating cases, which included recirculation zones as far as 10 to 12 channel widths from the exit. A correlation relating maximum hot surface temperatures with the independent parameters was developed.