This chapter discusses the impacts of human-induced environmental change, mostly by reviewing this emerging literature. It focuses on behavioral and physiological responses and also discusses their links to individual fitness. The chapter highlights parallels between the well-studied field of urban ornithology and the less established evidence from urban herpetology. It identifies research gaps and sets an agenda for future work. The chapter shows that lizards will provide especially fruitful subjects in attempts to disentangle whether and how such mechanisms of success are adopted, because they are often easily studied in both the field and the laboratory. It summarizes a few factors associated with plasticity: learning and innovation, and the influence of personality variation. The consistency of food availability in urban areas has facilitated survival in harsh climatic conditions and thus many urban-tolerant birds live in colder regions than their nonurban counterparts.