An issue that focuses clearly on the difference between market and book values is accounting for reserves in the extractive industries. The primary determinant of the value of a minerals or oil-and-producer is the value of the reserves it controls. Hence, one might expect that managers acting to maximise the value of the firm would try to account for the value of reserves in a credible way. However, we show that financial-statement recognition of reserve values is rare. We review the reasons for the general reluctance to recognise reserve values in financial statements and comment on the few exceptions.