The real answer here is - It depends.
The key to resume writing is relevance and so essentially you want to make the best possible case. You want to get the employer's attention as recruiters do the 20-30 second resume power scan.
If you do find that you are running beyond a page or even two, use some of the following layout techniques to help with page management.
1. Experiment with smaller margins. Microsoft Word has a default 1.25" margin. Experiment with .7" or .8".
2. Use tables and hide borders to make more efficient use of horizontal space.
3. Try a slightly smaller font.
4. Use text boxes to align information and use less space.
If you do have to use multiple pages, make sure your contact information appears on each page and heading is consistent.
Feel free to get a free resume critique from BullsEyeResumes.com, if you want to avoid rolling to the next page.