The approach adopted in this paper is to examine the development of Australian agriculture during the twentieth century in the context of its relationships with the rest of the Australian economy. The broad outline of this approach is similar to that adopted in Godden (1997, Figure 1) and is summarised in Table A.1.1. The key relationships of farm production – viewed via production, technology, input prices, structure and agricultural services – are with natural resource processes (climate, land, water), marketing systems, trade, market conditions, physical and social infrastructure, and inter-sectoral linkages. The more metaphysical role of agriculture, including its political context, is viewed through selected social and political “visions” of key opinion makers. Using these themes, two approaches are possible. One approach would be to follow each theme through the century. An alternative approach – adopted in this paper to emphasise the contemporaneous interactions of the themes in generating the evolution of agriculture – is to view the inter-relationships among the themes within time-slices of the century. The four “slices” used in this analysis are: 1900-1930 (Peace, War and Peace); 1930-1950 (Depression, War and Recovery); 1950-1970 (Good Times Plateau); and 1970-1999 (On the Slippery Slope). In this second approach, each theme can be followed through the time slices.