When examining the acquisition of the F-35 Joint Strike Fighter (JSF) by most western defence departments, the close historical and military connections between these countries with the United States only go so far in terms of an explanation for why some have adopted this platform and others have not. Adoption is by no means automatic and the features of large military platform procurement processes, which are both long-term and involve very large expenditures, with their idiosyncratic nature, multiple actors and strategic policy directions, have played an important role in this area, just as they have when purchasing warships and other military equipment. In this chapter, we compare how Australia and Canada chose to operate when considering the replacement of their ageing F-18 multirole fighters. Again, this process features two very similar countries and the same weapons system, and the different outcome each has had in this case again reveals the significant factors concerning the processes which led to those decisions, and the impact of politics in explaining both the commonalities and differences in the defence procurement approaches of the two countries.