What do you wear to run when it's cold?
Say in the 30's, then 20's.
Colder than that and Im staying in.

I like light layering with either some poly or another wicking synthetic. I sometimes wear a nylon windbreaker and usually a hat and pair of gloves.
Nothing to heavy 'cause you're gonna' get warm after about fifteen to twenty minutes.

I run all winter and have developed a pretty good system. I wear windpants if it's below freezing with a pair of tights underneath. The wind layer is important for me to keep my knees warm. At that temp I'll also wear a poly top, turtleneck, thin brown hardware store gloves, and a head band. After October when the afternoon light is bad I use an orange safety vest with reflectors tape and add an led headlamp this time of year. If it's 20 degrees I'll add an upper shell. Below that I use a hat instead of the headband and fleece gloves. I'm comfortable with temps down to zero if it's not windy.

Used to be I'd race in shorts and a singlet and wear a lot of Ben-Gay on the exposed parts (just remember to wash your hands before going to the bathroom - that stuff burns).

These days I like to dress a little more, but still try for as little as I can get away with, but I rarely expose my arms and legs when it's cold - I particularly like to keep the knees and leg muscles comfortable. I picked up a Nike ACG shirt last year at one of their outlets - sort of fleece stuff, zippered neck, very nice. Road Runner Sports does some nice heavy weight tights / shirts too which I find are reasonably water resistant (check out their outlet specials). I also wear Wind Briefs (they have a nylon panel in the front) to keep the tackle a little cosier when it dips below 20 or so.

Oh, and they were the subject of some debate here when I bought them last year, and much of what the naysayers said was true about my Salomon GTX gore-tex shoes (when it's raining hard or you go through deep water they fill up and don't drain well) but they do a great job of keeping my feet warm, including when I'm running through snow.

I'll second GeeVee on the windbriefs. VERY IMPORTANT when it's very cold and/or windy out.

Temps in the 50's - lycra tights
in the 40's - heavyweight lycra tights
30's - regular lycra tights with the old pair of lycra tights underneath
20's the heavyweight lycra tights with another lighter pair of lycra tights over them
10's - too cold to run

I highly recommend this scheme.

Are we talking 80's vintage style lycra?

I ran through my very first winter of running back in 88/89 wearing a pair of lycra spandex tights. I nearly froze my unit off on several occasions. With all the fun fabrics they make tights from these days I can't imagine winter running is lycra.

Kev

Bought a new pair of quasi-tights from a company called XC sports. Like very tight weave lycra that's soft lined. Supposed to be wind proof to 35 mph. Were expensive ($80) but cheaper than scholler. Still protect the "unit " though.

I'd give them the thumbs up.

They make a top also but have plenty of those. (no bottom jokes now!)

I wore my Scholler pants with light poly undies to the Eagles vs. Dallas game on 12/7 at the Linc Field in Philly. It was about 25 degrees out (the stadium is right off the Delaware River), and they were absolutely terrific.
I will definitely run in them this winter.