Introduction: Aging is often accompanied by decreased muscle mass, strength, and physical function. Resistance exercise may mitigate this loss; however, data are lacking that compare physical function of younger and older community-dwelling adults who do or do not include resistance training in their health and fitness routine. Therefore, the purpose of this study was to determine how skeletal muscle mass, strength, and physical function differ by age and resistance training status in community-dwelling adults. Methods: For this cross-sectional study, healthy younger (23.8 ± 0.4 yr) and older (68.7 ± 1.2 yr) adults (n = 76) were categorized into four groups based on resistance training status: younger resistance trained (YRT; n = 22), younger not resistance trained (YNT; n = 16), older resistance trained (ORT; n = 17), and older not resistance trained (ONT; n = 21). Participants performed stair climb, 30-s sit-to-stand, 6-min walk, and grip strength tests and had dual energy x-ray absorptiometry scans to measure skeletal muscle mass. Results: For stair climb, YRT, YNT, and ORT were faster than ONT (P ≤ 0.05). For 30-s sit-to-stand, YRT and ORT completed more reps than ONT and YNT (P ≤ 0.05; ORT vs ONT: d = 1.468; YRT vs YNT: d = 1.767). For 6-min walk, ORT, YRT, and YNT walked farther than ONT (P ≤ 0.05; ORT vs ONT: d = 1.007), and YRT walked farther than YNT (d = 0.764). Thirty-second sit-to-stand and 6-min walk were not different between ORT and YRT, 6-min walk and stair climb were not different between ORT and YNT, and grip strength and lean leg mass were not different between ONT and ORT (P > 0.05). Conclusion: Older adults who engage in regular resistance training can maintain physical function levels similar to that of younger adults. Additionally, these data provide evidence-based support that resistance training performed by community-dwelling adults on their own based on American College of Sports Medicine guidelines translates to real-world benefits to mitigate age-related functional decline.