Combine water, yeast, and sugar in small bowl. Let sit 5 minutes, or until yeast begins to look bubbly.
Pour yeast mixture into a large bowl and add olive oil, flour and salt. Mix until a soft dough forms.
Knead dough on a floured surface until smooth. Let rest 20 minutes.
Preheat oven to 450 degrees.
Press dough into a pizza shape on parchment paper or lightly greased pizza pan. Pierce dough with a fork, every few inches across dough.
Spread dough with ranch dressing.
Sprinkle with taco meat and cheese.
Bake at 450 degrees for 12-15 minutes.
Add favorite taco toppings on warm pizza. Slice and serve immediately.
Drizzle each slice with taco sauce, sour cream, or salsa.