1) Background: Self-determination theory (SDT) claims that need supportive behavior is related to the satisfaction of the basic psychological needs: autonomy, relatedness and competence. The student-teacher relationship is of special interest to understand mechanisms of physical activity behavior change in physical education (PE). (2) Methods: In this cross-sectional study, 481 girls answered a German version of the Basic Psychological Need Satisfaction (BPNS) in PE Scale. Contrary to previous studies, the psychometric properties of this scale were examined by multilevel confirmatory factor analysis. (3) Results: A model with three latent factors on both levels showed acceptable fit and all items showed significant factor loadings. Although one item was excluded due to psychometric reasons, the scale showed good internal consistencies; α = 0.85 at the individual level and α = 0.84 at the class level. Subscales' internal consistency at the individual levels was good, while at class level, the scores differed from poor to good. Small significant correlations of BPNS with moderate to vigorous physical activity support criterion validity. (4) Conclusion: The 11-item scale is a valid measurement tool to assess BPNS in PE and further application in the school setting would broaden the insights into the psychological impacts of SDT in PE.Clearly, we must also consider the environmental factors and individual circumstances which influence PA behavior [8]. Initially, the environment must provide an opportunity and motivational processes must be triggered so that the individual engages in PA. A sub-theory of the self-determination theory (SDT) explains the types of motivation. The organismic integration theory differentiates the degree of behavior regulation on a self-determination continuum, ranging from amotivation to intrinsic motivation (see Figure 1) [9]. Total lack of motivation characterizes amotivation. At the level of external regulation, the individual acts completely heteronomously, influenced by external interventions, such as reward and punishment. In this sense, an individual shows controlled extrinsic motivation, which includes also introjected regulation. Characterized by a successive increase of autonomy, the identified and integrated regulation accounts for autonomous forms of extrinsic motivation. Ultimately, intrinsic motivation is characterized by the most autonomous behavior activated by individual volition, personal interest or an exciting challenge [9].