This paper identifies the core strategies pursued as firms make choices about sourcing and shoring of HR services. It draws attention to a range of variables that need to be measured to assess the effectiveness of these sourcing and shoring strategies. It presents a review of the business drivers for human resource outsourcing and identifies the strategic outcomes that should be used to determine success in this. A range of readiness factors are identified and included in Appendix 1. In order to help HR practitioners plan for their own approach, the paper also considers how the market for sourcing and shoring options is developing by analysing some data on the volume and scale of contemporary deals. This analysis is used to identify useful avenues of research that might help explain international differences in the HRO market. Finally, some future developments and challenges for HR functions are signalled by analysing both vendor strategies and issues for the retained HR business.