This article presents research to delineate the construct of instructor strategic ambiguity (ISA) and develop a measure. The first study analyzed instructor uses of ambiguity, identified 18 strategies, and classified them into four categories. The second study developed an Instructor Strategic Ambiguity Measure (ISAM) for the college classroom. This 15-item scale consisted of four factors: "application", "challenge", "assignments", and "leadership". The ISAM is positively correlated with learner empowerment, learning indicators, need for cognition, and student motivation, which offers evidence of construct validity. The results of the study suggest student perceptions of ISA complement instructor clarity.