Modeling, one of the tools of Design of Experiments (DoE), was employed to achieve an optimum set of parameters for the microencapsulation of mefenamic acid with cellulose acetate phthalate. A two-level full factorial design was utilized to run the experiments with several factors being investigated simultaneously. A modified emulsion solvent evaporation was the method of choice to formulate the microcapsules. Microscopic evaluation of the surface characteristics of the microcapsules was conducted using stereomicroscope and SEM. Regression analysis was performed to evaluate the effects of the factors - polymer:drug ratio(X1), amount of emulsifier(X2), and stirring rate(X3) - to percent yield, particle size, drug entrapment efficiency, and release kinetics. The microcapsules exhibited spherical shape with rough surface. Percent yield ranged from 77.33% to 92.39% among the formulations. Particle size ranged from 290.12 to 1162.12 μm, with stirring rate being a significant factor. Drug entrapment efficiency (DEE) ranged from 63.55 to 96.86%, with amount of emulsifier, and combined effects of polymer:drug ratio and amount of emulsifier being the significant factors. Using the predicted model, a desired particle size of 561.77 μm and a DEE of 93.70% can be achieved by setting X1 to 1.25:1, X2 to 4 mL, and X3 to 650 rpm. The release kinetics of most formulations best fit the Korsmeyer-Peppas Model. With all these information, it can be concluded that the factors under study may significantly affect the in vitro performance of the MA microcapsule.