Yes, some foundations contain ingredients which clog pores. Ingredients to avoid include mineral oil, glycerin, kaolin (clay) and even talc. I recommend Physician's Formula Cosmetics, especially their Mineral Make-Up. It comes in a compact and you apply it with a brush (don't use the brush they provide, get a regular Kabuki style brush). You get great coverage, it feels even better than not wearing make-up at all, and it is actually good for your skin.