The study examines the structure and function of explanatory practices ( Begründen ) in everyday German conversation. It indicates, among other things, the forms of explanation favoured by speakers operating in various contexts, e.g. on what occasions they opt for a grammatically unmarked construction as opposed to one introduced by a conjunction or some other grammatically marked connection. Syntactic, semantic, prosodic, and action-related parameters are discussed in their respective usage context. In addition to the empirical analysis the study also investigates issues connected with the representation of linguistic units in grammar and the lexicon.