In college, I was taught in resume workshops that you should always try to keep your resume to one page long, unless you had post-graduate academic research to showcase, in which case it was okay to go as long as two pages. I think the reason was that a one-page resume would be more concise and would be able to convey to a hiring manager what you were all about at a glance.
I used a one-page resume when I interviewed with my current employer. I summed up my job experiences with technology acronyms and pretty general statements about my responsibilities. I figured that I could get into more details during the interview. I got the job, but I found out later that a lot of people were skeptical about me since my resume was so short. Apparently, other people with the same amount of experience as me (about 11 years work experience) are submitting resumes that are at least two pages long, sometimes more. I was also told that I have a lot more experience than my resume indicated.
I talked to one of my employer's recruiters about this and he told me that I shouldn't be concerned with keeping my resume to one page. Two or more pages are normal. Today I tried to rewrite and update my resume using as many words as I wanted. Even still, I barely ended up with two pages. I guess I am not very good at writing resumes. I need help. Luckily, I'm not actively looking for another job right now.