My house was built in the 70's and has those white 12x12 ceiling tiles throughout. Can I cover them over with stucco or do I have to pull them all down. These things are ugly and Want to get rid of them.

Remove the ceiling tiles. They are tongue & groove tiles stapled up to firring strips. The weight of any spackle or stucco can pull them down.

You may have a nice ceiling behind them were all you may need is some touch up. You won't know until you remove the tiles.