On the first Tues of the month this bakery does Gluten Free items. I just bought some and they were wonderful. I got a chocolate chip cookie and cinnamon chip bread. Keep in mind that this bakery is a "gluten filled" bakery and they are mindful of cross contamination issues but it can't be guaranteed. I spoke with the owners while I was there and absolutely enjoyed them.
They do not have gluten free options and they make it seem like the end of the world if you try to order a sandwich without the bread. I am not ciliac so I can usually order like that and be fine but the last few times I've been in there they roll their eyes and slam my food around making it quite obvious I'm ruining their day. They charge the same price for a cup of tuna salad as they do for a full sandwich which is SO not worth it. If you really want a sandwich go to a little further down Mass Ave and Avenue Deli has GF bread and very friendly staff.
Great Harvest Bread Co. has excellent GF breads and muffins and their locations! The staff is wonderful and all of their products are usually baked fresh the same day!