What glue to use to stick windscreen mirror to windscreen?

none you can buy the double sided stickers for mirror at hallfords
There should be a little tube of it in the repair kit.

If not, prep (cleaning the area) is essential. Clean the area and make sure it is not greasy, either. A good super glue will work fine.
Araldite or any other epoxy resin type adhesive, superglue will just fracture with all the vibration.
Dont use super glue! - I did on my old fiesta & it cracked the windscreen.
Use one of those sticky-pad things for mirrors from Halfords.
No Nails - sticks absolutely anything!!
They sell that glue at auto parts stores.
When I was a driving instructor I had to have an extra mirror on the passenger side and so had the same problem. They sell double sided stickers - the size of a small plaster - in car shops such as Halfords. These are purpose made and work quite well. They're less messy than glue too.
one pack epoxy with a special primer solution - try a main vehicle dealer - you ll get a better product than by going to halfords - it may be more expensive but its not the kind of thing you wanna take chances on is it ?? any main manafacturer dealer should get it for you
Super Glue or Wood Glue
superglue works fine.drive off road alot and my mirror is still there! cheap and easy..just watch your fingers :)
If you mean a windshield go to the parts store and they have kits just for it. Follow the directions very carefully or it wont work.Also before you remove the old glue mark the outside of the windshield with a crayon or tape so you know where to put the piece and the rounded edge goes to the top.
There are adhesives specifically made for this. Do not use epoxies of super glue.

Rear view mirror adhesive.

From the "windscreen" terminology, I will assume that you are not in the US, so I will have to keep this a general answer as brands, companies in the US aren't the same as in EU or other markets.

Here it's made by companies like 3M, VersaChem, Bell, Henkle. If all else fails, ask a local glass/shop or body shop where to get some.
Double sided stickers or "evo stick"
I used crazy glue and it worked well. It needed time to dry though before manipulating it. (Overnight)
windscreen mirror glue
Monkey glue is good, or is it Gorilla glue.
Don't use normal/super glue to attach mirror. In heat will either melt or damage window. Use proper glue eg halfords. Clean area free of grease etc. Attach mirror but DO NOT touch/move it for 24hrs. Perfect.
special mirror glue,avaialble at any parts house,but follow directions to the letter,do it in the shade
it's glass / metal bonding glue
pop into your local windscreen company and they'll sort it for you for about £10.00 it would be much cheaper to do this than buy the glue
Try cement, it normally works (not bricks and mortar cement! metal cement, glass cement, maybe even plastic cement).
call into your local rac autowindscreens they will do it for a reasonable price , plus you can be sure it wont come off again , the pads you buy are no good , and the wrong glue will crack your screen.