The paper aims to outline a theory of the verbal particle which can predict when a Hungarian verb takes a verbal particle and when it does not. It argues that the verbal particle appears in sentences describing complex events, and it is a secondary predicate predicated of the theme argument (hence it is barred from unergative sentences with no theme). It has three subtypes: the resultative particle, predicating the resulting state of a theme undergoing a change of state; the terminative particle, predicating the resulting location of a theme undergoing a change of location, and the locative particle, predicating the location of a theme whose existence or spatial configuration is asserted. Since the subject of predication must be specific, sentences with a non-specific theme can have no particle.