This chapter reviews concepts associated with infectious disease outbreaks, including disease surveillance, mechanisms used to detect outbreaks, and the epidemiological steps used to investigate an outbreak. We catalogue both routine and novel laboratory detection methods that can be used in an outbreak setting and examples in which laboratory testing played a central role. We introduce resources that readers can access when facing a known or novel pathogen in the context of an outbreak, including agencies that perform sophisticated surveillance and outbreak investigation. Emphasis is placed on the importance of thinking about the world health community with the stark rise in globalization, and the epidemiological players at each level from local to international are listed. In past editions of the text, the focus was largely foodborne outbreaks; this chapter expands the focus to include many different types of pathogens and settings for outbreaks.