Liao, T, Li, L, and Wang, YT. Effects of functional strength training program on movement quality and fitness performance among girls aged 12–13 years. J Strength Cond Res 33(6): 1534–1541, 2019—The purpose of this study is to evaluate the effects of a 12-week intervention of functional strength training (FST) on movement quality and fitness performance among 12- to 13-year-old untrained girls. One hundred forty-four girls (age 12.47 ± 0.57 years) were randomly assigned to the FST group and traditional strength training (TST) group. The FST group underwent 10 functional movement corrective exercises in the first 6 weeks and 10 functional strength promotion exercises in the following 6 weeks, whereas the TST group did 10 TST exercises with progressive intensity in 12 weeks. The training was 3 times per week and 45 min per session for both groups. The subjects were tested at the beginning and at the end of the intervention on movement quality and fitness performance variables. To compare the 2 groups pretest vs. posttests, analysis of variance with mixed model analysis of variance, paired t-test and independent t-test, and 2 × 2 contingency chi-squared analysis were used. The main time-by-group interaction effect of the total score of Functional Movement Screen (FMS) showed FST group significantly better than TST group explicitly (p ≤ 0.05). Differences between groups were detected for individual components in FMS test, injury-related problem items of FMS, and fitness performance variables. Although TST group increased the muscular strength significantly (p ≤ 0.05), the FST group has significant improvements on more variables such as deep squat and trunk stability, muscular strength, flexibility, and power (p ≤ 0.05). In comparison with TST program, FST program may be more effective on the improvements of movement quality, muscular strength, flexibility, and power among untrained healthy girls aged 12–13 years, and may result in better health promotion and injury prevention as well.