We introduce a new theoretical perspective for predicting effective monitoring, which involves a two-stage logic. First, we focus on individual directors, arguing that effective monitoring is highly likely when a given director possesses certain qualities. Based on prior research not previously coalesced, we set forth this baseline proposition: a director's likelihood of being an effective monitor in any given domain (say, financial matters) is greatly increased when he or she has all four of the following qualities: independence, expertise in that domain, bandwidth, and motivation. Second, we extend this quadrilateral model--or quad model--to make propositions at the board level. We argue that it is not sufficient for these four qualities to be distributed among all directors on a given board, since this makes it likely there will be no directors who can rise to the challenging task of monitoring. We propose that having just one quad-qualified director will be more predictive of board efficacy than will be any customary board descriptors. And we posit that if a board has two or more quad-qualified directors who can bolster and amplify each other, the company's likelihood of governance failures will be especially reduced. We discuss theoretical and practical implications and lay out a research agenda