This paper describes the development and predictions of a model that depicts the two-phase flow within an internally mixed air-assisted liquid atomizer using a statistical Weber number criterion. The main objective of this study is to develop an analytical tool that could be used in the design of internally mixed injectors and to predict the injector's flow and spray characteristics under different operating conditions. Basic conservation equations, along with appropriate boundary conditions, are used to model the two-phase air-liquid flow inside the injector. A statistically distributed Weber number criterion is used to estimate the sizes of the droplets being produced in the process. The liquid flow rates and mean droplet sizes, predicted by the model, are compared with the experimental data and they are found to be in fair agreement with each other.