Due to the worldwide health impacts of antibiotic resistant pathogens, scientists are increasingly interested in the role of wastewater treatment plants (WWTPs) as a sink and source for antibiotic resistant bacteria and their genes. This chapter discusses the implications for the spread of resistance genes within the wider environment. It also discusses the methodological considerations relevant to the study of antibiotic resistance in complex microbial communities. WWTPs are considered hot spots of microbial diversity and resistance because they receive contaminated wastewater from diverse sources and contain a variety of different environments with dense bacterial loads. Given the potential impacts of antibiotic resistant bacteria on human and animal health, the need for further research to support robust risk assessment and management of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in wastewater environments is clear.