This chapter focuses on systematic reviews of injury studies and discusses the structured process of reviews that involve several steps. A well focused question allows clear decisions to be made about what research to include in the systematic review and how to summarize it. The most commonly used sources are electronic bibliographic databases. Consultation with an experienced librarian helps to identify electronic databases likely to contain citations relevant to the specific research questions. Once identified, studies must be assessed to determine whether they meet inclusion criteria. Titles, abstracts, and keywords may be sufficient to exclude many studies. The chapter explains why a systematic review is done. It presents a meta-analysis of randomized controlled trials of the effect of albumin supplementation on mortality in critically ill and injured patients. Protocols for systematic reviews and completed reviews are peer reviewed and published in the Cochrane Library.