Swarms of agents exhibit advantages over a comparable group of solitary agents. One advantage is the ability for swarm agents to localize relative to the group using spatial relationships between many agents to achieve accurate relative position information. This is particularly important in GPS-denied environments where there are limited positioning options. Many applications exist for relative positioning, such as collision avoidance, formation flying, and patterned weapon delivery. Although there are many technologies that can be employed for relative localization, this report focuses on Atmel and Nanotron narrowband RF ranging products. Atmel transceivers are briefly evaluated but do not meet the US Army Research Laboratorys (ARLs) sampling rate and range requirements. Nanotron transceivers are more thoroughly evaluated and are shown to be promising products for ARLs swarm localization needs. The results of successful swarm localization experiments with 6 agents are presented.