This investigation evaluated the use of OMNI-Resistance Exercise Scale ratings of perceived exertion as a method for selecting training intensities that are appropriate for improving muscular fitness. 20 women (M = 21.3 yr., SD = 2.2) completed a one-repetition maximum for the chest press and knee extension. Participants returned for three sessions during which they were asked to select resistances which elicited the feelings of exertion associated with ratings of 3 (i.e., Easy to Somewhat easy), 6 (i.e., Somewhat hard) and 9 (i.e., Hard to Extremely hard). The average percentage of maximum lifted at a 3, 6, and 9 was 50, 69, and 88% for the chest press and 56, 74, and 90% for the knee extension, respectively. Effect sizes indicated large differences across the three ratings of perceived exertion within sessions and small differences between sessions. Intraclass correlation coefficients ranged from .69 to .95. The results indicated that OMNI-Resistance Exercise Scale ratings of 3, 6, and 9 can be used to accurately and reliably select intensities that are appropriate for improving muscular fitness.