High-intensity resistance training is effective at improving muscular strength, but its impact on functional fitness, body composition, cognitive function, and health-related quality of life remains uncertain. The purpose of this study was to examine the impact of 12-weeks of high-intensity resistance training on muscular strength, functional fitness, body composition, cognitive function, and health-related quality of life among community dwelling women over the age of 75 years. After completing baseline assessments, nineteen women were randomly assigned to a high-intensity resistance training group or a non-weight lifting active control group. Participants exercised two days per week at a local senior activity center. Eight exercises were included in the program: chest press, bent-over row, lateral raise, biceps curl, triceps extension, heel raises, knee curl, and seated knee extension. Sixteen participants (89.5%) completed the 12-week program. Participants in the high-intensity resistance training group (n = 10) significantly improved muscular strength, dynamic balance, and chair stand ability, more than participants in the control group (n = 6). Observed improvements in balance, fat mass, and waist circumference in the high-intensity resistance training group were similar to those in the control group. In addition, there was a non-significant trend toward improved cognition in both groups. Based on these results, it was concluded that high-intensity resistance training is an effective way to improve muscular strength, body composition, and physical functioning. The impact on cognitive function requires further study, but preliminary results are positive.