Using a colloidal particle scattering apparatus, we have observed shear-driven formation of particle doublets near a wall for latex and emulsion systems. For the latex system, capture is in the expected stable downstream position. For the emulsion system, capture occurs upstream from the fixed particle. Furthermore, the frequency of capture is found to depend on pH in agreement with rheology results. Computer simulations have been performed to examine the criteria for capture in this case, and, of necessity, a novel potential is introduced. Good comparison can be obtained between simulation and experiment when surface charge variations linked to pH are invoked as the key variable.