This note explores Smith’s employment of the concept of ‘productive labour’, a concept which commentators have frequently found problematic. We suggest that Smith’s difficulty in formulating a satisfactory definition of ‘productive labour’ stems from the fact that he seems to have had in mind - and to have tried to combine - two different (but only independently valid), concepts of productive labour: one (anticipating Marx) in respect of labour whose employment yields surplus value to the capitalist, the other (presaging Sraffa) focusing on labour employed in certain necessary or ‘basic’ industries within the economy