This chapter discusses Health Benefit Groups (HBGs)/Healthcare Resource Groups (HRG) matrices, which seek to summarize existing information about a health service as a basis for discussions and decisions. It seeks to identify some of the potential benefits and costs of HBGs. The chapter draws on the experience of Greater Glasgow Health Board (GGHB) as the pilot site for sets of matrices covering breast, lung and colorectal cancer between October 1996 and June 1997. HBGs offer a framework for discussions between purchasers, providers, and other stakeholders regarding the development of health services by describing the current service using the best available data and presenting the opportunity for examining the consequences of changes and nature of work in terms of activity and costs. The barriers to realizing the potential of HBGs include ability to complete matrices from existing data sources and the quality of the data obtainable from sources, valuation of resource use, choice of HBGs, and inclusion of outcome measures.