Since the terrorist attacks on the United States in September 2001, there has been an increase in the presence of temporary overt security in public places considered for future terrorist attacks. However, despite the appearance of these security features, there has been little research conducted by criminologists or other urban scholars on the social impact of these measures. In this chapter the author notes that as security measures increase in public arenas thought to be at risk of terrorist attacks, so do questions concerning the potential social impacts of these measures. The measures in question consist of the use of temporary, overt, and ad hoc protective protocols, such as Jersey-style cement barriers, marked vehicles, uniformed police officers, and fencing. This chapter offers a model for predicting the impact of security measures in public spaces on people’s perceptions of risk and fear. A connection is established between the fear of crime and the fear of a terrorist attack. It is argued that security measures, though installed to provide safety and protection, may actually contribute to fear and increased perception of risk. It is recommended that policy development should proceed with caution. The outcomes of fear and perception of risk may vary depending on who uses the space and for what purpose. Discussion questions and references