Is this an honest question? I mean, really? I'm as pro-legalization as they come, but it is well documented (and well known) that yes marijuana is addictive. For example, you could start at http://en.wikipedia.org/wiki/Cannabis_dependence, then http://scholar.google.com/scholar?hl=en&q=marijuana+addictio..., and work your way through 5 decades of research from there.