The authors of this volume's stimulus papers have taken on the challenge of developing measures of teachers' mathematical knowledge for teaching (MKT). This task involves multiple decisions and considerations, including: (1) How does one specify the body of knowledge being assessed? What warrants are offered for those choices?; (2) How does one describe competence/performance in the domain? On what basis is proficiency judged?; and (3) What kinds of tasks are chosen to use for examining competence, and how are they be scored? What implications do those choices have for: (a) cost?; (b) meaningfulness?; and (c) psychometric solidity? Each of these decisions entails consequences. In this article, the author frames some of those consequences and points to issues raised by the decisions made by the authors. (Contains 1 footnote.)