Background The Pain Attitudes and Beliefs Scale (PABS) for Physical Therapists aims to measure clinicians' biomedical and biopsychosocial treatment orientations regarding nonspecific low back pain. Objective The objective of this study was to assess whether the PABS can differentiate between subgroups of physical therapists hypothesized to differ in treatment orientations. Design This study was a cross-sectional survey. Methods The PABS was completed by 662 Norwegian physical therapists with a diversity of professional backgrounds. Twenty-four a priori hypotheses on expected differences in PABS scores were formulated. Sufficient discriminative ability was defined as a minimum of 75% confirmed hypotheses. Hypotheses on differences in scores were tested for the biomedical and biopsychosocial subscales separately as well as for combinations of the 2 subscales, representing responders with high biomedical and low biopsychosocial PABS scores and vice versa. Results Of the 24 hypotheses, only 15 (62.5%) were confirmed. Between-group differences concerning the separate subscales were small, varying from 0.63 to 1.70 scale points, representing values up to 6.0% of the total subscale ranges. Between-group differences were larger when combined subscales were used, varying from 1.80 to 6.70 points, representing values up to 25.1% of the total subscale ranges. Despite little spread in scores, 24% of respondents demonstrated extreme attitudes. Limitations The lack of convincing scientific evidence from previous research on differences in attitudes and beliefs between physical therapists was a limitation for the formulation of hypotheses. Conclusions Discriminative validity of separate subscales of the PABS was not supported. Combining the 2 subscales into global treatment attitudes enabled better discrimination. Little spread in biomedical and biopsychosocial orientations explains why more than one-third of the hypotheses were not confirmed. Either Norwegian physical therapists are basically similar in their treatment orientation or the PABS is not able to detect any differences between them.