I'm on Poser 6 so that may be a problem, I never did much with dynamics in P5... so it could be an issue with the differences in the versions! I tried the same experiment in P6, moving the choreographed group into the default dynamic groups AND leaving the floor unchecked for collision. The clothing dropped thru the floor but did not stretch thru the figure as your render shows. So you may have found something there! great! mike