Children and adolescents should engage in a variety of activities to develop muscular strength and motor skill performance in tasks such as running, jumping, and throwing. Resistance training and weightlifting are safe and effective methods to improve the athleticism of youth males. The overarching research question of this thesis was “is resistance training more beneficial with or without weightlifting for adolescent athletes?” Chapter 1 serves to provide background information, a rationale for the research, the purpose and significance of the thesis, and the thesis structure. Chapter 2 is a narrative review of existing models of youth development. These existing models highlight the trainability of all fitness components in youth through common resistance training methods, such as traditional strength training, plyometrics, and weightlifting. Chapter 3 provides an applied example of how practitioners can effectively implement these resistance training methods within secondary school curriculum. Specifically, recommendations regarding periodization and delivering the program are given to assist physical education teachers and coaches working with youth athletes. Chapter 4 examined the influence of maturity offset, strength, and movement competency on sprinting, jumping, and upper body power. Notably, relative strength was significantly correlated to all motor skill tasks (r = 0.28-0.61), reinforcing the idea that practitioners should prioritize strength when working with adolescents. Chapter 5 investigated how motor skills develop after an academic year of combined resistance training (CRT) or combined resistance training with weightlifting (CRT&WL) (28 total training weeks). There were no differences between improvements in various motor skills when comparing both groups. The time course of adaptation was similar between groups but was variable dependent. Movement competency and strength improved more during the first half of the training program, while sprint, jump, and throw performance improved more in the second half of the training program. This suggests youth need higher training intensities to stimulate expression of their recently developed strength into other motor skills. Chapter 6 examined how the CRT and CRT&WL training programs affect lower-extremity injury risk factors and resistance training skill. The CRT made significant improvements in tuck jump performance, whereas both training groups made significant improvements in resistance training skill after the year. Chapter 7 includes an overall summary, which suggests that both CRT and CRT&WL are effective for improving the athleticism of adolescent males.