This article examines the relationship between firm size and public sector tendering. The findings show that size, measured by employee number, significantly influences small and medium sized enterprises’ (SMEs) tendering resources, behaviour and success; as such, micro-enterprises are resource-disadvantaged, tender less often and have lower success rates compared to small and medium-sized firms. These findings indicate that SMEs are heterogeneous tenderers, and point to the need for more focused research on how SME characteristics influence ability and willingness to tender.