A basic philosophy course at Catholic University this fall costs $420, half that much if students take the class in the new evening program instead of during the day. But three subway stops away, at the University of the District of Columbia (UDC), a similar course would cost a District resident only $16.80.

The dramatic differences in tuition costs at Washington area colleges and universities were highlighted by a new survey of 17 institutions in the District, Norther Virginia and Maryland.

Educators confirmed the accuracy of the survey's figures but cautioned that tuition costs aren't necessarily related to the quality of education. They blamed the price differences mainly on variations in school endowments and government support.

Local- or state-supported colleges also generally charge students who come from other areas more than they charge their own residents.

The survey, published by "The Metro Consumer," an independent monthly, shows that students attending area schools may pay as little as $5.60 a credit hour or as much as $140.

Catholic University generally charges the most, while UDC charges the least, according to the survey.

But many of the schools have complex rules governing tuition charges, and the fees for the same course may vary from student to student.

For instance, Mount Vernon College charges a part-time student who returns to the classroom after an absence of at least three years $57 a credit hour. But if the student has been out of school less than three years, she would have to pay $114.

At UDC the $5.60 rate is available only to students who take from four to 11 hours of classes.

Although the prices cited are for courses taken for credit by part-time students, the figures also apply to many full-time programs. Only tuition per credit-hour was considered in the survey. Other special fees, such as required recreation charges or late registration costs, were excluded.

"Take the amount of money that a state gives its university and add what students there pay and it will be about what students at a private school in that region pay," said John Gilheany, dean of the new evening program at Catholic University.

He said the nature of the school also can produce significant differences in tuition costs.

"An undergraduate school tends to be less than a graduate school," he said.

Tuition fees generally were lowest at government-affiliated institutions, including UDC, Northern Virginia Community College and Prince George's Community College.

But residency requirements can make a big difference.

At UDC the $16.80 philosophy course would cost eight times that much for a non-resident.

The fee would more than triple at the Northern Virginia school, from $25.50 for a resident to $84 for a non-resident. It would double -- from $54 to $123 -- at Prince George's Community College for a student who lives in Maryland but outside Prince George's County.

And if the person comes from outside Maryland to Prince George's, the charge jumps to $213.

Thomas Houston, 31, a full-time data processing employe at American Telephone and Telegraph Co. in downtown Washington, lives in Prince George's County and said he picked his college largely on the basis of cost.

"I need a degree to get a higher-paying position," said Houston, a part-time student. "No matter how much knowledge you have, there is no advancement without that degree." And Prince George's, he said, was cheaper than the University of Maryland.