Oh, this thread must have slipped through.. Sorry, I can't be of very much help either, as I don't do ReWire anymore. Basically to make Reason be a ReWire slave of Reaper you initialize the apropriate ReWire plugin one of Reaper's tracks. It looks like any other FX plugin, find it in the ReWire folder of the FX list window (or type rewire into the filter of the FX list). If you chose the plugin "ReWire: Reason", Reason will open automatically as a ReWire slave, so you can route your MIDI via Reaper to Reason. This is very different from other ReWire implementations, as one of Reaper's tracks does all the connection and you route everything else as sends from/to that track. Another restriction: You can only have 16 channels of MIDI going to Reason (Could be this has changed in the meantime). Hope this helps a little. There's been quite a bunch of threads about it, so I'd think a forum search would come up with more details. (tip, use google search, if the forum search engine doesn't work well. I have this link bookmarked: )