These work!  I have a terrible time finding a good fit in shoes.  As suggested, I bought 1/2 size larger than the length of my street shoe measurement.  I measure a 6 in length, but have a terrible time finding one that actually fits properly.  Dance shoes seem to be more consistent in sizing than street shoes, so when they say your street shoe size pay attention to what your foot actually measures, not the size shoe you may wear (which may vary by manufacturer).  You might find that these run narrow.  I have a problem finding shoes that aren't too wide, and these are not too wide for me, as many Mediums are.  And dance shoes tend to have a more precise fit, without excessive toe room.  So I don't slide forward or sideways in this shoe.  I bought it for Zumba because I can't find a sneaker in which I don't slide around, and it's no fun trying to dance (or do any kind of step) when you go sliding around inside your shoe; if you slide inside your shoe your footing feels really unstable.  This is the first dance sneaker that I've found that does fit me well.  And it's ever so soft and flexible!