The size premium is an important valuation issue for two reasons: (1) it is difficult to estimate; and (2) its inclusion in deriving a cost of capital can have a material effect on the outcome of a valuation assignment. This article provides an overview of the current status of the size effect and size premia in Australia, examples of cases from Australian courts and tribunals in which size premia have been considered, and the issues and challenges faced in estimating size premia within the Australian market.