A resume should be as long as necessary to convince a hiring manager to contact the job applicant. While a one-page resume is often the standard recommendation, there is no resume length rule that works for everyone. It is more important to highlight factors relevant to the position, such as career objective, experience, accomplishments and education.
Monster recommends keeping a resume to one page when the job applicant has fewer than 10 years of relevant experience, has had only one or two long-term positions, or is pursuing a significantly different career field and doesn't have a lot of relevant experience. A two-page resume is a good idea for those who have more than 10 years of relevant work experience or whose experience includes detailed technical skills that require room to explain.
No matter how many pages the resume is, keep it as concise as possible, sticking to the key selling points. Remove any items unrelated to the position being applied for. A job applicant shouldn't list volunteer work in a completely different field or any coursework, unless she is recently out of school. Include keywords from the job description when describing previous work experience to make the resume stand out.