The short answer is "yes," you can paint siding. But I'm wondering if it will be worth it depending on how much siding you need to paint and how it will perform over time. If you're talking about siding that covers an entire house, there are some advantages to simply replacing it. Vinyl expands and contracts significantly with changes of outdoor heat and cold, more so than any other building material. So you'd be asking your new paint coating to hold up to a lot of flexing over time. Adding a dark coating will attract more heat and will probably increase the expansion as well. I'd also be concerned about the paint "gluing" the siding panels together at the seams, then cracking loose with changes in the weather. You may even see gaps open and close with white color stripes peeking out. If painting is really your best option, you'll need to make sure you wash the siding very well, maybe even use some kind of de-glosser. The folks at my local Sherwin-Williams paint store have helped me select plastic paint (to coat thick plastic lumber) in the past, with very good results. Trust them to give you the right formula and techniques (this is important). Plan on at least three days for "curing" between coats. I expect you'll probably need at least two coats as well (hmm . . . the labor hours are adding up). But let's think a little deeper. What if you could recoup some money on future energy bills to help pay for the change in the house's exterior color? I think I'd rather pay a good vinyl siding contractor to install brand new vinyl in my favorite color, and do it under warranty, than spend at least as much money on painting labor (or try do all that work myself). While you're at it, have the installer add a thin layer of foam insulation behind the siding, or maybe upgrade to foam-backed siding. And if you don't have a nice tight house wrap under your existing siding, this would be a great time to add that vapor barrier, caulk, and paste the edges down around the window and doors to reduce air penetration. In my experience, siding replacement is a one to two-day job for an experienced installer, and it will pay you dividends in energy saving. But the siding material will cost more than paint. Painting is more labor intensive and will not hold up as well over time, but your paint materials will be less. You'll have to do the math. If you're only treating a small area for appearance (for example, to improve curb appeal to sell the house), painting is the old reliable choice. Oh, and be a good neighbor: choose a color that's in keeping with the character for your neighborhood!