This article provides an overview of the use of the framing concept in mass communication research. It focuses on the questions what a frame is and how it is measured, how variation in framing can be explained and what the effects of media framing are. Specific attention will be paid to the sociological origins of framing. The article concludes with recommendations for future research. It argues that a more systematic and conceptually precise measurement of framing is warranted and suggests how the scope of frame-building and framing-effects studies can be extended.