This paper provides an exposition of the information sector approach. Concept and measurement of the information sector are discussed in detail. Findings for Australia are reported, including so far unpublished data on the labour force employed in the primary and secondary information sector. The total information sector accounted for about 41.5 per cent of the Australian labour force and about 31 per cent of value added in 1981. More than half of all the people employed in informational occupations were employed in the secondary information sector. The need for the standardisation of the measurement of the information sector is emphasised. Improvements in input-output modelling and other avenues for research are suggested.