OBJECTIVES Evaluate the effects of a weight-bearing neuromuscular training program on 2D and 3D lower extremity kinematics during a single leg step down. DESIGN Pre-test, post-test quasi experimental. SETTING Laboratory. PARTICIPANTS Sixty nine healthy females performed a single leg step down. The 20 females with the most medial knee orientation during this task participated in this study (20.0 yr (1.6 yr), 167.9 cm (6.0 cm), 63.2 kg (8.3 kg)). MAIN OUTCOME MEASURES 2D knee frontal plane projection angle (FPPA) and 3D lower extremity joint (hip and knee) and segment (pelvis and femur) angles during a single leg step down before and after training were compared using paired t-tests. Pearson correlation coefficients were used to measure the association of 2D and 3D kinematic changes following training. RESULTS Knee FPPA decreased 4.6° after training (P < 0.001). Hip flexion (P < 0.001) and hip adduction (P = 0.04) increased after training. However, no other 3D joint kinematic changes were observed. Segment angle changes included decreased femoral internal rotation (P = 0.008) and adduction (P = 0.08) and increased anterior pelvic tilt (P < 0.001) and contralateral pelvic drop (P = 0.02). The association between changes in 2D and 3D joint kinematics ranged from 0.12 to 0.34. CONCLUSIONS Exercises intended to improve altered lower extremity kinematics may reduce medial knee 2D FPPA values during a single leg step down. However, this 2D change may not be linked with any specific change in 3D joint kinematics.