There is general agreement between the ACS and USPSTF with regard to the following:

Most cases of cervical cancer are related to the Human Papilloma Virus. There is an effective vaccine for girls under 26 years of age to prevent such infection which is recommended
Under age 21: No screening
Ages 21 to 30: Pap smear every 3 years
Ages 30 to 65: Pap smear with HPV (Human Papilloma Virus) testing every 5 years, or Pap smears alonge every 3 years.
After age 65: No further testing IF all testing prior to that age is current and normal.
After hysterectomy for reasons unrelated to cervical cancer, no testing is needed.