There has been an increase in ulnar-sided wrist pain among tennis players. The purpose of this study was to establish a normative dataset of kinematic and electromyography (EMG) data during the forehand and two-handed backhand groundstrokes. In total, 20 adolescent United States Tennis Association (USTA) ranked tennis players (11/20 Male, Age = 15.0 ± 1.8 years, Height = 1.7 ± 1.1 m, BMI = 21.3 ± 3.4 kg/m2, 18/20 right-arm dominant) participated in this study. Kinematics (range of motion and angular velocity) and EMG data were simultaneously acquired during the forehand and two-handed backhand groundstrokes. Minimal differences were found between groupings of age, sex, and USTA ranking. The two-handed backhand groundstroke is characterized by bilaterally flexed elbows and ulnarly deviated wrists, with a flexed wrist and pronated forearm on the non-dominant side and an extended wrist and supinated forearm on the dominant side. EMG activation occurs bilaterally by peak backswing. The forehand groundstroke is characterized by a flexed elbow, pronated forearm, and ulnarly deviated and extended wrist. The wrist is at maximum ulnar deviation at ball impact. This study established an initial foundation for normative data for the forehand and two-handed backhand groundstrokes, which can be used for injury detection, rehabilitation, prevention, and ultimately performance improvement of tennis athletes.