This research analyzes the phenomena of grouping or platooning during the evacuation of seven stairwells within four different high-rise buildings. The purpose of this research is to investigate the changes occurring to platoons as they descend the stairs in order to incorporate the results into computer egress models. Platoons are found to travel in three distinct patterns: elongation, compression, and equilibrium. Also, platoons are found to remain unchanged, add new occupants, merge with other platoons, or fragment during their descent within a stairwell. The results demonstrate that a trend exists between patterns of platoon elongation leading to fragmentation and platoon compression leading to platoons merging. The majority of the platoons identified are found to consist of one person and remain unchanged as they descend between floors. Finally, a qualitative comparison between the platoons analyzed and the platoons identified in the behavioral computer egress model Pathfinder, is presented.