Teachers with an autonomy-supportive style rely on different instructional behaviors to motivate their students than do teachers with a controlling style. In the present investigation, the authors tested which of these instructional behaviors actually correlated positively or negatively with students' autonomy. The authors used Deci, Spiegel, Ryan, Koestner, and Kauffman's (1982) teacher-student laboratory paradigm to randomly assign 72 pairs of same-sex preservice teachers into the role of either teacher or student. From videotapes of the 10-min instructional episode, raters scored 11 hypothesized autonomy-supportive behaviors and 10 hypothesized controlling behaviors. Correlational analyses confirmed that students perceived the functional significance of 8 instructional behaviors as autonomy supports and 6 instructional behaviors as autonomy thwarts. The discussion focuses on the interpretation and classroom implications of these data.