Abstract:Multi-particle correlation analysis has proven to be a powerful tool in exploring the underlying mechanisms of particle production in high energy hadronic collisions. In this talk, recent results on two-particle correlations in p+p and A+A collisions at PHOBOS over a large acceptance will be presented. The observed complex two-dimensional ($\Delta\eta$, $\Delta\phi$) correlation structure has a natural interpretation in the context of an independent cluster model. The extracted cluster size and decay width show an intriguing dependence on the size and geometry of the collision system. Furthermore, new studies of limited acceptance effect on the cluster parameters will also be discussed.