Background: The increase in anterior cruciate ligament (ACL) injuries in pediatric patients and the high failure rate reported in the literature in this population are driving surgeons to search for specific techniques to better restore knee stability. Recent literature has reported that the combination of lateral extra-articular tenodesis (LET) and ACL reconstruction improves outcomes in high-risk patients. However, such advantages in pediatric patients have been infrequently evaluated. Purpose: To assess whether adding LET to ACL reconstruction can significantly improve knee stability, clinical outcomes, and failure rates in pediatric patients. Study Design: Cohort study; Level of evidence, 3. Methods: A multicentric study involving 3 orthopaedic teaching centers was conducted to evaluate pediatric patients aged between 12 and 16 years who had undergone primary ACL reconstruction using a physeal-sparing femoral tunnel drilling technique. A minimum 2-year follow-up evaluation was required. Based on the surgical technique performed, the patients were divided into 2 group. The patients in group 1 underwent an isolated arthroscopic ACL reconstruction, while the patients in group 2 had an arthroscopic ACL reconstruction in combination with a modified Lemaire LET procedure. Group 1 was a historical control cohort of patients, whereas group 2 was prospectively enrolled. All the patients included in the present study were clinically evaluated using the Pediatric International Knee Documentation Committee (Pedi-IKDC) subjective score and the Pediatric Functional Activity Brief Scale (Pedi-FABS) score. Anteroposterior knee stability was measured using the KT-1000 knee ligament arthrometer, and the objective pivot-shift evaluation was documented using a triaxial accelerometer (Kinematic Rapid Assessment [KiRA]). The included patients also underwent a standardized radiological protocol to evaluate leg-length discrepancies, axial deviation, and degenerative signs preoperatively and at last follow-up. Results: This study included 66 pediatric patients with an anatomic hybrid ACL reconstruction using an autologous 4-strand hamstring graft. In group 1, there were 34 patients (mean age, 13.5 +/- 1.2 years), while 32 patients (mean age, 13.8 +/- 1.4 years) were included in group 2. The clinical outcome scores showed no difference between the 2 groups (Pedi-IKDC, P = .072; Pedi-FABS, P = .180). Nevertheless, the patients in group 2 had better anteroposterior stability measured using a KT-1000 arthrometer (1.9 +/- 1.1 mm in group 1 vs 0.8 +/- 0.8 mm in group 2; P = .031), as well as better rotational stability measured using the KiRA (-0.59 +/- 1.05 m/s(2) in group 2 vs 0.98 +/- 1.12 m/s(2) in group 1; P = .012). The patients in group 1 returned to sports at the same competitive level at a rate of 82.4%, while patients included in group 2 returned at the same competitive level in 90.6% of the cases without a significant difference between the 2 groups (P = .059). No leg-length discrepancies were found between the 2 groups at last follow-up (P = .881). Two patients displayed an increased valgus deformity of 3 degrees on the operated limb at last follow-up (1 patient in group 1 and 1 patient in group 2). Group 1 had a significatively higher cumulative failure rate (14.7% vs 6.3%; P = .021). No intra- or postoperative complications was observed between the 2 groups. Conclusion: Performing a modified Lemaire LET along with an ACL reconstruction with hamstring graft in pediatric patients reduced the cumulative failure rate and improved objective stability with no increase in intra- or postoperative complications. No significant difference was found between the 2 groups in terms of patient-reported outcomes or in the return-to-sports activity.