Abstract: When two small drops or bubbles approach each other, a dimpled thin film is formed between them. A model is developed for the dynamics of the thinning film with tangential immobile interfaces, in which the London-van der Waals forces are taken into consideration. The model predicts the coalescence time, which is the time required for the thinning and rupture of the liquid film, by giving only the radii of the two drops and the required physical properties of the bulk fluid and interface. A more general expression for coalescence time is derived. The predicted result is in good agreement with previous experimental results.