What is the father of the groom supposed to wear to the wedding? I've seen some instances where the groom's dad wears a tux and others where he just wears something nice, like slacks and a shirt. I was under the impression that only the men in the ceremony (i.e., my dad, my FI, and his groomsmen) had to wear a tux. I really don't care what my FFIL wears, just as long as he's comfortable, but my FMIL insists that he should wear a tux (and I should mention that he doesn't want to). Thoughts?