The correct manipulation of particle size distribution in suspension polymerization is important because particle size determines the product applicability and processability. Methyl methacrylate suspension polymerization was studied in order to determine the effect of operational parameters in manipulating the particle size distribution (PSD) while keeping suspension stability. The effects of stirring rate, stabilizer concentration, and stabilizer addition time were evaluated on particle size distribution, Sauter mean diameter, and suspension stability. Stabilizer concentration affected particle sizes but at the expense of system stability as low amounts of stabilizer led to uncontrolled coagulation of the particles. Changing the stirring rate was efficient in manipulating particle sizes although its increase led to the broadening of the PSDs while reducing the Sauter mean diameter. The moment stabilizer was fed has shown to be a very efficient way to manipulate the PSD as delaying the stabilizer addition increased the Sauter mean diameter and narrowed the distributions. However, there was a limit in increasing the addition time as adding the stabilizer at higher conversions compromised the suspension stability.