This chapter discusses the characteristics and limitations of diagnostic tests for Bordetella pertussis infection, including bacterial culture, polymerase chain reaction, and serology. It then discusses surveillance for pertussis at the population level in high- and low-income settings, outlining the interplay of clinical, laboratory, and surveillance criteria in the identification and reporting of pertussis cases. The characteristics of pertussis surveillance systems are related to both detection and reporting of pertussis and can change, even within countries, if changes in diagnostic practice occur, making comparisons over time problematic. These considerations have significant implications for optimal surveillance of pertussis in different settings and assessment of resurgence, as also discussed in Chapter 4 on pertussis epidemiology.