Lisa, I've used Color Mechanic, and while it works, I think one can get the same results using either Hue/Saturation in the manner Jonathan described, or the Selective Color adjustment in PSCS2. I didn't find Color Mechanic all that it's cracked-up to be in terms of really isolating the color you want to adjust. But one other observation on this matter in general - I have often found that if there is a problem with one colour, it often means that the overall colour balance is somehow off, but is more noticeable with one colour than any other. Hence when I spot this issue in some of my images, the first thing I do is verify the overall colouor balance before resorting to selective colour adjustments. Of course, this doesn't apply if the objective is to intentionally change a correct colour in a balanced image to something else for whatever reason.