In this brief article, the author notes that the empirical study of coordinated collective motion (CCM) has often been built upon the theoretical foundation of mathematical models and computer simulation of behavior. One key assumption of CCM models is that individuals' movement behavior is influenced by rules of proximity-a balance of attraction and repulsion tendencies depending on how close an immediate neighbor is. When individuals are moving in groups, these rules therefore have a bearing on the alignment of individuals in space and time, and so also on the orientation and speed of movement of individuals. As Quera et al. (this issue) point out in a study, however, we have relatively little empirical evidence to support these key assumptions about orientation and speed of movement. Taken together, their study is significant in that it provides the movement detail to support key assumptions made by CCM models. (PsycINFO Database Record (c) 2019 APA, all rights reserved).