The Australian economy of the interwar period experienced noteworthy cyclical and secular trends. Severe cyclical fluctuations were associated with the international depression, often referred to as the ‘Great Slump’, which particularly afflicted Australia’s large traded sector, especially its cornerstone primary exporting industries. In the midst of this apparent dearth, however, came the ‘plenty’ of the initial stages of modernisation, which resulted from the broadening of the country’s economic base into new manufacturing industries. The general trends of economic activity are captured by national income data, while the expansion of particular industries has been contextualised by several authors, most notably Forster for the 1920s. Less clear, however, are the reasons for this structural diversification. One popular strain of argument lies in the ability of manufacturers to act as rent seekers, particularly through the protection offered by high tariffs and other forms of inducement together with a benign disregard of anti-competitive behaviour by successive governments. An alternative perspective associates structural change in this period with the reaping of new opportunities by ‘corporate leaders’ across a number of industries within sectors. In this paper we construct and analyse a time series of the profitability of industries in services and manufacturing, which enables us to examine the motivating factors behind structural change from the perspective of price signals, in the form of differences in absolute and relative rates of return on shareholder equity. This study is the first to use the business profits data for interwar Australia. Research on, or including, the interwar period has been undertaken recently for several other countries including Britain, Germany, France, and Spain with which some initial comparisons will be drawn.