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Abstract Background The lower quarter Y‐balance test (YBT‐LQ) has been recommended as a measure of dynamic postural control in the clinical setting; however, information about the relationship between performance on the YBT‐LQ and joint kinematics is limited. Thus, the kinematic predictors responsible for performance on the YBT‐LQ need to be identified for accurate evaluation of dynamic postural control. Objectives To identify the kinematic predictors that best explain variance in performance on the YBT‐LQ. Design Cross‐sectional design. Setting University motion analysis laboratory. Participants Thirty physically active participants. Methods All participants performed the YBT‐LQ. The kinematics of the trunk and lower extremity at maximal reach in each direction of the YBT‐LQ were monitored using a 3‐dimensional motion analysis system. Main Outcome Measurements The correlations between reach distance and joint kinematics were assessed using Pearson's correlation coefficient, and the best predictors of performance on the YBT‐LQ were determined using a stepwise multiple regression analysis. Results Ankle dorsiflexion was the best single predictor of normalized reach in the anterior direction of the YBT‐LQ ( r 2 = 0.50), and the combination of ankle dorsiflexion and trunk extension explained 65% of the variance in the anterior normalized reach. Hip flexion was the best single predictor of posteromedial ( r 2 = 0.60) and posterolateral ( r 2 = 0.71) normalized reaches of the YBT‐LQ. The combination of hip flexion and ipsilateral trunk bending and the combination of hip flexion and contralateral trunk bending accounted for 69% and 80% of the variance in the posteromedial and posterolateral normalized reaches of the YBT‐LQ, respectively. Conclusions These findings provide useful information on the relative contribution of joint kinematics to performance on the YBT‐LQ when evaluating dynamic postural control.