In this study, we analyze the effects of asynchronism and neighborhood size on the collective motion of multi-agent systems. Many studies performed on the collective motion of self propelled particle systems or basically a class of multi-agent systems are modeled to be synchronous. However, in nature and in robotic applications the autonomous agents mostly act asynchronously. Therefore, a model based on the asynchronous actions of agents is developed. The agents/particles are assumed to move with constant speed and asynchronously update their direction of motion based on a nearest-neighbors rule. Based on these rules simulations are performed and the effects of asynchronism and neighborhood size on the clustering performance are investigated. © Springer-Verlag Berlin Heidelberg 2006.