Super cute sweater! No need to size up in my opinion. In fact, I feel it may run slightly big. I'm 5'1 and 142 pounds with an hourglass figure. The small fit nicely with a little bit of looseness in the back. If you are any smaller than me and want a more fitted look, than this sweater may not work for you. Otherwise, super soft and comfortable sweater. Not too think or too thin. Highly recommend!