I needed a plain white polo for a Halloween costume, and I couldn't find one anywhere (who would have thought they'd be that hard to find in October!!)  The price on Amazone w/Prime for this Dickies one was perfect ($10) and arrived exactly when I needed it.  I would have ordered the Women's Dickie polo, but they were not available in white with Prime shippig so I took a chance on the Jrs sizing.  I wear a Misses size Medium (6/8) and ordered the Jrs Large & XLRG because I was undecided on which would fit best.  The Jrs. Large fits great.  It is a slightly fitted style and longer length, which I prefer opposed to the baggy style.  So if you wear a misses Medium, go for the Jrs. Large!