Background and Purpose. An active strategy was developed for the implementation of the clinical guidelines on physical therapy for patients with low back pain. The effect of this strategy on patients' physical functioning, coping strategy, and beliefs regarding their low back pain was studied. Subjects. One hundred thirteen primary care physical therapists treated a total of 500 patients. Methods. The physical therapists were randomly assigned to 1 of 2 groups. The control group received the guidelines by mail (standard passive method of dissemination). The intervention group, in contrast, received an additional active training strategy consisting of 2 sessions with education, group discussion, role playing, feedback, and reminders. Patients with low back pain, treated by the participating therapists, completed questionnaires on physical functioning, pain, sick leave, coping, and beliefs. Results. Physical functioning and pain in the 2 groups improved substantially in the first 12 weeks. Multilevel longitudinal analysis showed no differences between the 2 groups on any outcome measure during follow-up. Discussion and Conclusion. The authors found no additional benefit to applying an active strategy to implement the physical therapy guidelines for patients with low back pain. Active implementation strategies are not recommended if patient outcomes are to be improved.