I get asked this question a lot, so posting the answer here seems logical. We generally feel that if you have more than five years of experience, you do not need to keep your resume to one page. This is because by five years in the work force, most people have begun to get a taste of management and/or mentoring experience, are moving up the chain and should be able to communicate growing responsibilities and a more strategic thought process.
At this same juncture, you don’t need to include details of school and extracurricular activities, or GPA. At five years post-graduation, you are deep enough into your career that it is the work that speaks for who you are and what you can do, not the activities you pursued while in school.
If, however, you are barely out of school, then these things are good on a resume for showing what your work experience does not yet prove: That you are high-energy and can multi-task.
And, please, PLEASE don’t send me a resume in 8 pt font just to get all to squeeze onto one page. I am old and cranky now that I’m in my mid-thirties, if I can’t read it without squinting, it goes into the circular file. If you have to use less than 11 pt font to keep your document to one page, then go back and edit it down. Then edit, and edit some more.