This paper examines the context of critical reading and considers how it can best be taught. The paper also includes some reflections on the current "state of the art" in critical reading in an English for Special Purposes (ESP) or English as a Second Language (ESL) context. The paper details a series of attempts to develop a set of questions that can be used in teaching critical reading, and introduces "set theory" (a math concept) to ESP. The paper suggests six steps for the use of set theory in the teaching of reading, as well as a set of questions which systematize and break down some sub-skills in critical reading: (1) comprehension questions; (2) readership questions; (3) reader's appreciation; (4) text applicability; and (5) text or writer questions. The paper argues that: critical reading is an essential part of the genuine response to text; there is a need for teachable techniques for helping readers to learn how to react critically to texts; critical reading can and usually should be done on all text types, from poems to telephone directories; and critical reading is applicable not only to a detailed level of comprehension but also to general and to main points comprehension. (Three figures of data are included; a list of "Dishonest Tricks," 9 notes, and 17 references are attached.) (RAE)