COLLEGE students who choose not to drink alcohol or use other drugs are finding increased support on campus these days - at least from the housing department.At Clark University here in Worcester, Mass., students looking for a respite from keg parties and drunken housemates are provided apartments in a charming, three-decker house on campus. "More and more students are becoming less and less tolerant of drunken, disruptive behavior," says David M. Milstone, assistant dean of students at Clark University. A survey conducted on the campus last year showed strong enough student interest to warrant a special housing situation for those shunning alcohol and other drugs. "It's important that there's a place for people who need or want a substance-free environment," says Susan Gamache, a resident assistant in the dorm and a senior at the college. When Clark established the "Substance Awareness House" this fall, it furthered a nationwide trend toward accommodating students who want a living environment that supports their lifestyle. Some students who choose this alternative living arrangement are recovering from a pattern of substance abuse, or they are children of alcoholics, says Mr. Milstone. Other students simply want to separate themselves from behavior they don't wish to participate in. "It's my choice" not to drink alcohol or do drugs, says Hope Catcher, a senior at Clark and a resident of the Substance Awareness House. "I feel confident about it." "This is something that goes a step beyond providing information and educational programs and workshops," says Alan Berkowitz, director of the counseling center at Hobart and William Smith Colleges in Geneva, N. Y. "It's in effect restructuring the campus environment to make non-use [of alcohol and other drugs] more acceptable and encouraged." Dr. Berkowitz has conducted research showing that students consistently overestimate the alcohol and drug use of their peers. "So when students misperceive the norm on campus, they tend to adjust their own behavior to fit into the norm," he says. "If you create a substance-free living environment, that lets students know everyone else is actually not using alcohol and other drugs. It removes the element of peer pressure or guessing in order to fit in. ... It also sends a message to the whole campus that you can be cool and not drink." About five years ago, Hobart founded the SHAC (Students Have a Choice) substance-free house for students. Residents began having nonalcoholic parties on a regular basis. The house became known as a place where students could go for a good party on the weekends without the peer pressure, says Berkowitz. "There are more and more students who are interested in this [housing] option," says Jim Earle, assistant dean for Hobart residence life. He expects the college to have two substance-free residence halls next year. At Denison University in Granville, Ohio, the drug-free dorm has grown from a single floor three years ago to full occupancy of a two-story residence hall. Student demand was so strong this year that 28 students were placed on a waiting list, according to Jeffrey W. Pollard, director of the counseling center. At Occidental College in Los Angeles, students may not return to the dorm if they have consumed alcohol within the previous four hours. Despite such rules, the number of people choosing to live in the dorm has doubled since it was instituted two years ago, according to Bart Verry, director of residence life. At Rollins College in Winter Park, Fla., residential life director Mike Lawrence established "Wellness Floors" last year. "I wanted our program to be more positive than 'drug-free,' which sounds pretty negative," he says. The 30 student residents have an interest in total fitness. They participate in group "fun runs" and floor-wide aerobics classes. The connection may not be definite but of the 33 residence areas at Rollins College, students on the "Wellness Floors" had the third-highest grade-point average and caused the least amount of damage to dorm property.