What other products are you using? I found that certain eye creams, concealers, and foundation made my eyeliner and mascara smudge more frequently, especially during warmer weather. A nice gel or cream eyeliner like MAC Fluidline can survive a marathon! (Literally.)

Try wearing eye shadow primer on top of your lid, as well as under your eye--particularly focusing on the outer corners. Trust me, it makes a difference!

Thanks for the suggestions ladies. The shape of my eyes also doesn't lend itself well to under-eyeliner, which compounds the problem. I will give these tips a try.

Totally second the MAC Fluidline . Not much lasts on me but that stuff is amazing. Make Up For Ever Aqua Liner Liquid is also really good.

I like Fluidline, but I love Aqua Black from Make Up For Ever (in a black opaque jar). It stays creamy no matter what, even at the bottom of the jar. When it dries (it dries fast on your eyes), it doesn't budge (it's waterproof, smudge proof). My favorite thing is that since it's in an opaque jar, the cream stays jet black because light can't get into it and change the pigment, which seems to happen to me when I get a clear glass jar of cream/gel liner. I even used this for face painting.

I personally like powder shadow dabbed on with a flat brush instead of liner. If it does smudge, at least you can wipe it off, easily. However, there are some really good long-wear liner products including some really inexpensive longwear cream liners in a dual pot, by MARK. Just be sure not to wear anything creamy under your eye as that will make the issue worse. If you really like the look of liner and want it permanently, you can tattoo it on, although I don't really suggest it in case styles change

I second the idea for eyeshadow primer. I just started wearing it recently on a whim (I always felt like it wasn't a *necessary* step) and now I won't switch back. I've noticed not only does it keep my eyeshadow looking fresh, my eyeliner still looks flawless even at the end of the day.