The present study investigated whether an autonomy-supportive intervention influenced students' need satisfaction, achievement emotions, and strategies of self-regulated learning differently depending on several student characteristics. The study was conducted with a sample of 345 9th-grade students in 17 physics classrooms who were randomly assigned to an experimental or a control condition. In both conditions, their physics teachers taught a standardized teaching unit on heat transfer that either entailed autonomy support (via provision of choices, provision of rationales, and informational language) or was taught using the regular teaching style. A range of student characteristics (gender, prior physics grades, physics-related effort, interest, extrinsic motivation, self-efficacy, and perceived autonomy in physics class) were considered as potential moderators. The differential effectiveness of the autonomy-supportive intervention was investigated using the EffecLiteR approach. Both the average effects of the intervention and conditional effects (i.e., distinct interactions of the intervention with each of the student characteristics) were investigated. Analyzing average treatment effects revealed that the autonomy-supportive intervention had a positive impact on all outcomes. The intervention fostered need satisfaction, positive achievement emotions, and learning behaviors and reduced negative emotions. Moreover, the results showed that students' prior grades moderated the effects of the intervention with regard to 3 outcomes: Students with higher grades reported greater optional choices, joy and effort. These findings point to the benefits of providing autonomy support in physics and demonstrate the relevance of conducting a detailed analysis of the differential effects of motivational interventions.