ONE page only, unless you have 10+ yrs experience, in a variety of positions/companies. For entry-level jobs, if the resume is more than one page, it means the essential parts are likely to get overlooked. I usually spend less than 2 minutes reading a resume, if nothing catches my eyes, then I move on to the next one.
My advice: Keep ONLY the most relevant experience in your resume, plus your education of course (Start from the highest, and goes back to Bachelor's degree). Get professional help if you are not sure how to edit your resume.