After discovering this thread just today and reading through the whole thing, I'd like to add a few comments of my own.

I have the impression that the discussion began by considering the role of an individual instrumentalist's role when asked to accompany a solo performer, and later evolved into a seminar on arranging parts for larger groups. I'd like to backtrack a bit first and toss in a few observations on joining in with another to make a duet.

Someone way-back-when asked "what about accompanyng yourself?" I thought this question was deserving of more response than it got. A rank beginner will accompany himself by simply repeating the same simple strumming, or the same fingerpicking pattern, for one verse after another. The more sophisticated approach, of course, is to introduce some kind of change (hopefully subtle) with each verse, so that the performance as a whole gains structure and builds up to something.

This approach is of course equally desirable whether we're talking about a solo singer playing his own instrument, or an accompanyist trying to enhance a partner's performance.

I'd like to emphasize that by endorsing a style of accompaniment that "builds" tension and interest from verse to verse, I am NOT suggesting speeding up the tempo -- quite the contrary. One should be able to introduce all kinds of changes to feeling and even to rhytmic patterns, even while keeping to the strictest metronomic beat.

While the consensus opinion that the accompanyist should carefully listen to the "lead" performer is well-taken, it should be taken with a grain of salt. In many cases, the "second" guitar (or whatever instrument) can make a valuable contribution to the whole by keeping the tempo and reining in a tendency that the singer may have of unconsciously pushing the rhythm ever faster.

This is certainly what is supposed to happen in jazz groups, blues bands, etc., where the "rhythm section" provides the foundation for the other players to build upon. In an ideal folkie-type duet, the "lead" performer may be more prominently heard by the audience while putting out the "top" part of the total sound, but it may be the "backup" artist who is actually providing the beat which the singer follows. (Of course, the accompanyist should still be listening attentively while holding that steady beat, assuming that he/she is capable of playing different licks with different feelings while mantaining the tempo.) In the ideal realization of what I'm talking about, *both* performers are "leading" the duo -- one rhythmically and the other expressively of, for want of a better word, emotionally.

I do realize that a certain class of the most lyrical tunes may benefit from a loose approach to rhythm, but my personal feeling is that the "freedom" to ignore time signatures is often abused, and is the single most common characteristic of bad, tasteless amatuerism. Self-indulgent self-styled blues singers are, to my mind, the worst. (I have to qualify this by saying that I hear much less of this today than 20-30 years ago, but then again, I'm not spending nearly as much time these days hanging out with my fellow amatuer musicians in pass-the-basket clubs.) I can sum up my reaction this way: if you can't count to four twelve times in a row without dropping a beat, I don't want to listen to your caterwauling!