Although there is a vast body of secondary literature on Mark 4:11-12, the interpretation of this passage has been dominated by source, form, and redaction critical methods which have tended to limit, or even discount, the importance of these verses in the Gospel. This study, in contrast, uses reader response criticism. Graeco-Roman rhetoric, and sociological approaches as aids to understanding the literary and social functions of Mark 4:11-12. Since the methods used in this study are still fairly novel in New Testament research, the first two chapters provide a detailed introduction to interpreting Mark from the perspectives of reader response, ancient literary theory (Chapter 1), and social setting (Chapter 2). The main questions posed in these chapters are: 'how would Mark have been evaluated literarily by a Graeco-Roman reader?'; and 'what was the Gospel used for in its original setting?' After a survey of the literature on Mark 4:11-12 (Chapter 3), material in Mark which seems to echo these verses verbally or thematically is reviewed in detail (Chapter 4), and the passage is studied in its immediate context, the parable chapter (Mark 4:1-34) (Chapter 5). Two final chapters summarize the findings of the study from literary and sociological perspectives. Mark 4:11-12, it is concluded, is not, as several important interpreters (E. Schweizer, T.H. Weeden, H. Raisanen) have asserted, a 'foreign element' to be ascribed to pre-Marcan tradition, but integral to the Gospel as a literary whole, and to the function of the book in its original setting. Mark 4:11-12, part of Mark's secrecy motif, focuses the reader's attention on certain aspects of the Gospel's eschatological teaching (parables, miracle stories, confession scenes, apocalyptic discourse), and served the needs of early Christian missionaries anxiously awaiting the parousia of the son of man and the establishment of the kingdom of God.