Composite particles for Chemical Mechanical Polishing (CMP) have the potential to allow users to tailor slurries to their specific needs. In this work, we present a simple approach to creating self-assembled composite particles consisting of a silica core and ceria shell. The particles are designed to maximize their 'chemical tooth' against silicon oxide. We propose a mechanism for the assembly of these particles and present a mathematical model of their overall surface charge. This model agrees well with experimental analysis of the particle zeta-potential and settling behaviour. The composite particles are used to polish PECVD silicon oxide. A twenty-fold increase in oxide polish rate is observed when using the composite particles, compared to polishing with either silica or ceria alone. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.jes113470] All rights reserved.