To achieve the goal of high luminosity in a proton synchrotron, one can either increase the beam intensity or lower the transverse emittance. This article, based on our design study for the Medium Energy Booster of the Superconducting Super Collider, contains an analysis of a few mechanisms that could possibly cause the transverse emittance to grow in a proton synchrotron. To ensure that the emittance growth is within a tolerable level, some feasible precautions are suggested. Their improvements on beam quality are also described. © 1995American Institute of Physics