This study, which was informed by self-determination theory, examined the impact of an autonomy-based instructional intervention on the motivation and academic performance of American university students (N=219) enrolled in an elementary Spanish course. This study utilized a quasi-experimental design with the experimental group receiving an autonomy-based instructional intervention while a comparison group receiving a business as usual course experience. Both the experimental and comparison groups were exposed to the same curricular material, with the difference being that the experimental group was given the opportunity to apply autonomous decision-making to structuring their learning experience. The following research questions were examined: (1) Does the autonomy-based instructional intervention increase the motivation of elementary-level foreign language students to learn Spanish? (2) Does the autonomy-based instructional intervention increase the academic performance of elementary-level foreign language students in Spanish? (3) Does the autonomy-based instructional intervention increase the level of autonomy of elementary-level foreign language students in Spanish? Results showed improvement on both motivation and language performance. Neither autonomy nor motivation were related to improvements in students’ language performance.