What size are the leaves?

It looks like a Cissus, maybe C. rotundifolia.

Your plant needs more light. Notice how far apart leaves are from each other?? Toni

I agree it needs more light. Could it be a heart-leaf Philodendron (hederaceum?) Has it been repotted since you've had it?

Thank you for everyone's help! The largest leaves are almost 3in long. I re-potted it a little over a year ago, which helped, but maybe I didn't cut enough back??

It is not a Philodendron because the leaves are thick and crisp, like a succulent with thin leaves. If you bend the leaves they will break. Also the stems are only slightly pliable.

Toni, I haven't been able to find a picture of a Cissus that looks like my plant..or a Cissus rotundifolia. I only have west facing windows. I usually hang the plant to the side of the window in the picture. I will leave it right on the table in front of the window and see if it likes it there better....

I think that it might be one of the peperomias, though the name escapes me right now. Maybe P. scandens or a closely related cultivar? Though in much need of better light in its permanent location.

Ander, don't know if this is legal, but I'll give it a try.
There's numerous Cissus species...different shapes and colored leaves..

See if you can open this..It's from Top Tropical Nursery.

Oh well, Garden Web won't allow the link. I have one, but don't have a picture, and my camera isn't working.

You can Google Cissus. Toni

My plant looks like a peperomia incana but without the fuzz. Wait, but that comes with the 'incana' part! Still, this is the best likeness I've seen.

For the cissus, I did find a photo that resembled my plant, but it has toothed leaves (barely, but there) and mine have smooth edges.

I will keep looking, but thanks for all of the help!

Ander, you're right. I looked at my C. Peruvian..it has toothed-edges.
Think it gets 'toothier,' as it matures..lol

Perhaps, as Rhizo suggested, a Peperomia. There's many Pep species, from tiny to large leaves.

Since your plant has thick leaves, soil should dry between waterings. Thick leaves hold moisture. If it was my plant, I'd treat it like a succulent, with a little more humidity, and bright light. Toni

Thanks for the advice; this is what I needed to know. I'll have to change its location.