I use a carpeted floor all the time! Lay your backing down, wrong side up and pin it to the carpet in the corners and a couple of places along the sides, making sure it is flat and tight. Layer your batting and then the top, smoothing out each layer. THEN (this is how it works), slide a cutting mat on the carpet, under the backing and use the mat as something to pin against so you don't catch your carpet. I just did it last night - works great!