Thanks for your reply Oshyan. Although I still seem to be getting something wrong. I want to isolate a tree type and have everything else as a holdout, but when I group the tree type, other objects (a foreground bush in this example) is rendered as well. I have tried doing it two ways, one with just the tree in a group, and one with the tree in group and the bush in it's own group set to holdout. What am I doing wrong?