Do you want the final track to still be a MIDI track or do you want a final audio track? I just tried what Tod suggested above but it didn't work for me in combining multiple MIDI tracks into one composite track. This sounds like what you want to do based on what you said. I think that can be done though because I seem to remember doing it on accident a few times when first learning Reaper. I just don't remember what I did and it has never been necessary for me to do so. However, if you want to actually "bounce" multiple tracks down to one audio track, as in how one would have done it on an old analogue or digital multi-track recorder, there are a couple of options I know of. Though I think it may be worth pointing out that within the environment of Reaper it seems unnecessary to do so, at least to me, but you may have your reasons. Bouncing was once used to free up a limited amount of tracks and seems a little redundant in Reaper or any similar DAW. If it's CPU you want to conserve then freezing (or rendering) MIDI into audio will put your VSTs offline and do that job. One method to actually bounce is to create a folder track for all the tracks you want to bounce; right click in the fader area of the folder track. You will see a menu with record options. I personally don't know what most of them actually do. I tried several of the MIDI options and they don't seem to re-record the MIDI data. However, if you select "Record: output" and arm the folder to record and record as usual it will bounce whatever tracks are in said folder down to an audio track in real time. You can even tweak things in the playing tracks as it records just like one used to have to do back in the day.;) That's the easiest way I know and I've used this method on occasion to get certain un-automated effects recorded the way I want them. Another similar way would be to send the tracks you want to bounce to one receiving track and basically do the same procedure. I just think making a folder is quicker. EDIT: I just noticed that I also answered what is being asked .