Broiler chicken behavior is shaped by an interaction of genetic and environmental factors. This chapter focuses on the expression of natural behaviors, particularly those that are strongly motivated and potentially linked to positive emotions or affect. These include eating and drinking, foraging, dustbathing, preening, play, exploration, and social behaviors. In addition, the chapter examines how genetic selection for rapid growth and feed efficiency influences behavior, both directly and indirectly. The emotional impact of behavioral expression may be evidenced in two ways. One, the chickens’ willingness to engage in the behavior, and two, by their behavioral expression when the environment allows it. The influence of physical limitations, such as lameness and body weight, on behavioral expression is also explored. Additionally, the chapter addresses abnormal behaviors and normal behaviors that are not expressed, before concluding with a summary of challenges and opportunities for future research to better understand behavioral needs in broilers.