Yes. When it comes to layering skincare products, order matters. "In general, skincare products are layered from thinnest to thickest with the thinnest products being applied to the skin first," Dr. Hartman told us. "Serums are intended to deliver active ingredients deep into the skin and the moisturizer forms a seal to make the serums more efficacious." To effectively layer your serum and moisturizer, first rub the serum onto your face and neck. Then, wait for 30 to 60 seconds before applying your moisturizer on top.