I carefully measured our dog before selecting the right size. I decided that the X Large was the closest. Our dog is similar in size and shape to a Jack Russell Terrier. Her actual measurements (done via the method pictured on the listing) are Neck 12" Body Length from base of neck to base of tail 18" Chest 21" Measured right behind front legs. The X Large T Shirt size chart states the size as Neck 14" Body 15" Chest 21"FABRIC:I couldn't see the fabric on the listing anywhere, nor was it on the bag it came in, but there was a tag inside the shirt which stated 100% cotton. The fabric is very thick and tightly woven. I am VERY impressed with the fabric.EMBROIDERY AND COLOR: The embroidery was done beautifully. The color is more green and red instead of the turquoise and pink in the picture on the listing, but that's ok. They are nice soft colors and look more Christmassy anyway.SIZE: As you can see from the photo, the T Shirt fitted her very well given the extreme differences between the sizes and shapes of various dogs. It was a tiny bit snug around the neck but it was easily stretched out a little. Given that the sizing states for neck 14" and our dogs neck is only 12" if your dog has a 14" neck perhaps consider the next size up because I don't think that this would have been comfortable at all on a dog with a neck thicker than 12" I particularly didn't want the neck too large or she would have chewed on it so the snugness was ok. It is quite snug around her middle too, but the sizing is accurate and the next size up is 4" bigger, so I will just stretch this one out a tiny bit. I hope it keeps it's size and shape after washing (if it doesn't I will update this review)As soon as I put it on her (it was the first time she had worn clothes) she accepted it in an "Oh yeah, I wear clothes ALL the time" way. I thought we would have to get her used to it before she wore it to the Christmas Eve family gathering but there will be no need to phase it in. She seemed very comfortable in it and kept it on all evening (she always liked burrowing into blankets, and carries an old T Shirt of mine around with her so I thought she might be ok with it) Anyhow, she seemed to like it so much that now I am thinking I will get her another for more frequent wear and keep this one looking nice for Christmas.I love the other design from Parisian Pets that says "With a shirt this awesome who needs pants" Cute!