Creatine supplementation in close proximity to resistance training may be an important strategy for increasing muscle mass and strength; however, it is unknown whether creatine supplementation before or after resistance training is more effective for aging adults. Using a double-blind, repeated measures design, older adults (50–71 years) were randomized to 1 of 3 groups: creatine before (CR-B: n = 15; creatine (0.1 g/kg) immediately before resistance training and placebo (0.1 g/kg cornstarch maltodextrin) immediately after resistance training), creatine after (CR-A: n = 12; placebo immediately before resistance training and creatine immediately after resistance training), or placebo (PLA: n = 12; placebo immediately before and immediately after resistance training) for 32 weeks. Prior to and following the study, body composition (lean tissue, fat mass; dual-energy X-ray absorptiometry) and muscle strength (1-repetition maximum leg press and chest press) were assessed. There was an increase over time for lean tissue mass and muscle strength and a decrease in fat mass (p < 0.05). CR-A resulted in greater improvements in lean tissue mass (Δ 3.0 � 1.9 kg) compared with PLA (Δ 0.5 � 2.1 kg; p < 0.025). Creatine supplementation, independent of the timing of ingestion, increased muscle strength more than placebo (leg press: CR-B, Δ 36.6 � 26.6 kg; CR-A, Δ 40.8 � 38.4 kg; PLA, Δ 5.6 � 35.1 kg; chest press: CR-B, Δ 15.2 � 13.0 kg; CR-A, Δ 15.7 � 12.5 kg; PLA, Δ 1.9 � 14.7 kg; p < 0.025). Compared with resistance training alone, creatine supplementation improves muscle strength, with greater gains in lean tissue mass resulting from post-exercise creatine supplementation.