I'm not petite or super toned, a pretty average size 12.  The M/L fits just fine albeit a touch snug under the arms to begin with, but I either got used to it and/or it wasn't that bad.  There's not a ton of stretch to it, which is a good thing, as I've purchased another brand's dance shrug and you end up re-adjusting it all the time because the yarn stretches out.  These do not.  They are a nice weight, not too heavy, just right.  Looking forward to getting more.