Although procurement of COTS software for Defence applications has long included evaluation in terms of the products' respect for standards and norms, actual experience has often revealed shortcomings in the ability to deploy solutions based on these packages widely over a period of time. We look here at what additional factors need to be considered in order to make the use of COTS software more likely to bring continuing benefits over the life of an application system. The six aspects that are considered in the paper are: * Presentation interfaces * Release compatibility * Portability * Programming interfaces * Security interfaces Management interfaces