We examined the productive efficiency of the interior sawmilling industry in British Columbia using stochastic frontier analysis. Prior sawmilling studies using this method have neglected the multi-output nature of sawmills. To accommodate both lumber and chips as outputs, we used a ray production function and adopted it into the stochastic frontier framework. A translog functional form was specified with three inputs (i.e., capital, labour, and roundwood) and applied to five years (2003–2007) of mill specific production data. The ray production function is flexible allowing factor productivity to vary with the output mix. Results indicated the presence of both economies of scale and technical inefficiency. This suggested that a long-run equilibrium had not yet been reached during this time and might explain recent restructuring occurring in this region.