A recurring paradox in the contemporary K-12 classroom is that, although students educationally and developmentally benefit when teachers support their autonomy, teachers are often controlling during instruction. To understand and remedy this paradox, the article pursues three goals. First, the article characterizes the controlling style by defining it, articulating the conditions under which it is most likely to occur, linking it to poor student outcomes, explaining why it undermines these outcomes, identifying its manifest instructional behaviors, and differentiating it from an autonomy-supportive style. Second, the article identifies seven reasons to explain why the controlling style is so prevalent. These reasons show how pressures on teachers from above, from below, and from within can create classroom conditions that make the controlling style both understandable and commonplace. Third, the article offers a remedy to the paradox by articulating how teachers can become more autonomy supportive. Three essential tasks are discussed. Special attention is paid to practical examples of what teachers can do to support students' autonomy. (Contains 4 tables and 4 footnotes.)