Picking a health insurance plan for your college years is like taking a frustrating multiple choice test: More than one answer may be correct--or none of them may be. Generally, the easiest and perhaps best thing for most students is to continue coverage under their parents' policy. Full-time students are typically covered under most policies until the age of 23.

But be forewarned: If a parent belongs to an HMO with a local network of providers, the student may not be covered for anything outside the plan's service area except emergency care. A more open plan, like a preferred provider organization, may allow students to see doctors near school, but that may rack up hefty out-of-network charges.

Most colleges offer some type of health insurance plan, with the student health center acting as the primary care provider. Many schools require enrollment if the student is not covered under any other plan. But check the plan carefully. "Many plans offered by colleges are pretty bare bones," says Mila Kofman, assistant research professor at Georgetown University's Health Policy Institute. How bare is the care? Physicals, gynecological visits, and other preventive care may not be covered. College plans also may not cover pre-existing conditions, leaving you to underwrite your asthma medication or X-rays when that old knee injury flares up. Lifetime limits on coverage may be significantly lower, too.

Safety net. Some students may want to consider buying the college policy to supplement a parental plan. The college plan could pay for mental health services, for example, for much less money than the out-of-network cost under the parents' plan. But keep the parental policy for its higher lifetime limits, better drug coverage, and lack of exclusions on coverage of certain conditions. Annual premiums can range from $300 up to $3,000. Cornell University's health plan, for example, covers all pre-existing conditions and provides $1 million in lifetime coverage for an annual cost of $1,059.

Individual insurance policies are also worth investigating. As premiums rise with age and illness, plans for the young and healthy can run as low as $30 a month, rising to $200 or $300 a month depending on the size of the deductible and whether the insured has a serious medical condition like diabetes. Read the fine print carefully: These policies may not cover pre-existing conditions for a year and may exclude other conditions as well. -Michelle Andrews