Particularly for adolescent students, tools for measuring their experience of negatively consequential aspects of student-teacher relationships are limited even though evidence shows that keeping this group motivated in the classroom is especially challenging. Therefore, using basic psychological needs theory, this paper proposes a conceptualization of adolescent classroom psychological need thwarting by advancing a set of items to measure and empirically test the phenomenon. The outcome of this process is a new scale with psychometric properties that support its validity and usefulness for understanding an important dimension of adolescent classroom relational experiences. Specifically, empirical findings confirm the reliability and a priori hypothesized specification for the scale. Further, the new scale has the expected correlations with an external theoretically-related construct and demonstrates good measurement invariance. Together, the development of this type of instrument opens up the opportunity for more research, especially focusing on how the relational structure of the learning environment affects adolescent students.