ABSTRACT Introduction: Preliminary evidence in adults with spinal muscular atrophy (SMA) and in SMA animal models suggests exercise has potential benefits in improving or stabilizing muscle strength and motor function. Methods: We evaluated feasibility, safety, and effects on strength and motor function of a home‐based, supervised progressive resistance strength training exercise program in children with SMA types II and III. Up to 14 bilateral proximal muscles were exercised 3 times weekly for 12 weeks. Results: Nine children with SMA, aged 10.4 ± 3.8 years, completed the resistance training exercise program. Ninety percent of visits occurred per protocol. Training sessions were pain‐free (99.8%), and no study‐related adverse events occurred. Trends in improved strength and motor function were observed. Conclusions: A 12‐week supervised, home‐based, 3‐day/week progressive resistance training exercise program is feasible, safe, and well tolerated in children with SMA. These findings can inform future studies of exercise in SMA. Muscle Nerve 52: 559–567, 2015