Calisthenics, a form of resistance training, continue to increase in popularity; however, few studies have examined their effectiveness for muscle strength improvement. The purpose of this study was to compare progressive calisthenic push-up training (PUSH) to free weight bench press training (BENCH) as techniques to develop muscle strength and thickness. Twenty-three healthy, moderately trained males (mean ± SD: age 23 ± 6.8 years) were randomly assigned to PUSH (n=14) and BENCH (n=9), and trained three days per week for four weeks. Muscle thickness, seated medicine ball put, one repetition max bench press (1RM), and push-up progression (PUP) were measured pre- and post-training. Results revealed significant increases in 1RM (p<0.001) and PUP (p<0.05) for both groups post-training. The increase in PUP, however, was significantly greater for PUSH (p<0.001). This study is the first to demonstrate that calisthenics, using different progressive variations to maintain training principles, can improve upper body muscle strength.