The investigators will design and implement a randomized clinical trial to test, on a community-wide level, the effectiveness of managed care based tracking/reminder/recall on improving vaccination coverage among adolescents.

The investigators propose a randomized controlled trial to evaluate the effectiveness of reminder/recall for adolescents: 10,599 adolescents within the managed care organization (MCO) will be randomized into one of three arms: 1) mailed reminders, 2) autodialer telephone messages or 3) standard of care of their practice (no messages from the intervention).

Hypothesis 1: Reminder/recall will increase the receipt of immunizations and preventive services

Hypothesis 2: Telephone (autodialer) reminders will be more effective than mailed reminders

Hypothesis 3: The impact of reminders will be greatest for the most high-risk subgroups which have low baseline immunization rates.

Hypothesis 4: Mailed reminders will be more costly (and less effective) than telephone reminders.

Inclusion Criteria:

• Member of the Monroe Plan for Medical Care (managed care organization)
• Patient of a participating practice
• Ages 10.75 to <18 years of age

Exclusion Criteria:

• Member of the Monroe Plan for Medical care for less than 6 months
• ICD-9 diagnosis of 999.4 for anaphylactic reaction to a vaccine or its components.
• Encephalopathy within 7 days of a previous dose of a pertussis containing vaccine not attributable to another identifiable cause
• Guillain-Barre- ICD-9 code is 357.0

N/A- reviewed claims data