[SSJup81]

In the US, you can't attend college/university at all unless you've graduated from high school or have some equivalent of a high school diploma. High school is like a pre-requisite for college, I guess you could say. I don't think any school, here in the US anyway, allows students to attend any post-graduate school without having finished high school. The only exception I can think of, are high school students who take AP subjects, and just take them at a college campus as opposed to a high school one. I don't know how it is in Canada, though.