Building positive teacher-student relationships (TSR) is a central task for teachers. According to the person-centered approach, teachers create positive relationships by treating students with unconditional positive regard, empathic understanding, and genuineness. Numerous studies demonstrate the impact of person-centered teacher behavior for students' achievement and well-being. The effectiveness of person-centered behavior is supposed to be determined by underlying attitudes. Accordingly, person-centered attitudes should receive greater focus in both teacher education and TSR research. However, a suitable measurement instrument is currently lacking. Therefore, the APBS instrument was developed, a theoretically-grounded self-report questionnaire that measures pre-service teachers' attitudes on person-centered behavior toward students. In previous studies, the suitability of the test's content and internal structure were empirically examined using EFA. The present study investigated the internal structure using CFA, as well as the associations with external variables, in a sample of N = 1284 pre-service teachers from German universities (Mage = 23.3, SDage = 5.2; 79.8% female). Different factor models were tested and compared. The model with four first-order factors (unconditionality, empathic understanding, trust, genuineness) along with the APBS higher-order factor showed the best fit (?[superscript 2]/df(1504.868/520) = 2.894, p < 0.001; CFI = 0.968; RMSEA = 0.038). Both the four first-order scales ([omega]t* = 0.81-0.90), and the second-order scale ([omega]t* = 0.95) exhibited satisfactory internal consistency. In addition, structural regression and mediation analyses revealed mostly theory-consistent relationships with respondents' attachment representation, empathy and relational competence. In summary, the findings support the intended interpretation of APBS test scores. The questionnaire can be used as a measurement instrument in TSR research and as a self-exploration tool in teacher education.