I apply this at night because I find that my makeup does not seem compatible with this serum. However, this is a 5 stars product despite my inability to make it work with my makeup! At night, I apply it under the Resist barrier moisturizer with retinol and I wake up to smooth, glowing healthy looking skin. The serum glides on the skin and makes it feel so silky. My skin looks plump, even toned and smooth. I have read Paula's reviews for years on beautypedia, trying to find products that would work and now I could just kick myself for not trying her products sooner! I ordered right after Christmas and my skin is the best it's ever been after only one month of using her serums, moisturizer and exfoliants!