When intelligence analysts cannot rely solely on factual evidence to address questions of concern to US national security, they have to begin to employ judgment. In effect, when we do not know, we estimate. And when analysts estimate they depend on what I will call mind-set. For the purpose of this article, mind-set is the distillation of the intelligence analyst’s cumulative factual and conceptual knowledge into a framework for making estimative judgments on a complex subject. Case studies on Agency analytic performance indicate that analysts and managers alike do not pay their dues to this powerful phenomenon. Analytic procedures and practices, herein called tradecraft, that do not ensure against or otherwise combat mind-set put the resultant assessments at high risk of either being wrong or being unread.