A mechanistic model is developed for the prediction of annular two-phase flow behavior in gas wells. The model can predict annular flow characteristics, such as liquid film thickness, gas void fraction, and pressure gradient. It was evaluated against a data bank of 75 wells for which the pressure drop between the bottom of the well and the wellhead was available. The model was also compared with data from two wells with measured pressure profiles. Model predictions are in agreement with these data and superior to most commonly used correlations.