Hi Dan, There is currently no Chimera capability for moving atoms other than rotating about bonds. But I have been wanting to add mouse modes for moving and rotating sets of selected atoms around. Here is some Chimera code http://www.cgl.ucsf.edu/home/goddard/temp/moveselection.tar that adds a mouse mode to move selected atoms in the screen x and y directions with the mouse. The archive contains a directory called MoveSelection. Put it in your Chimera distribution in chimera/share or on Mac in Chimera.app/Contents/Resources/share Then when you start Chimera use menu entry Favorites / Preferences, and choose category "Mouse" from the preferences dialog. This shows the mouse modes table with the available modes along the top line. The last one is for moving selected atoms. Reassign a mouse button (say button 2) to this mode and you can move selected atoms. There is no undo. Tom