Because he always was smaller than almost everybody else, Dennis Brown grew up talking his way ouf of fights in the tough neighborhood around Eastern High.

Then one day, lined up at a theater box office, he saw hoodlums rob the person ahead of him. "I realized that if they had come up to me I had no way to defend myself. That's when I decided to do somthing about the situation."

The something was learning martial arts. Brown began working out with some friends and dabbled in most of the karate forms before chancing upon Willy Lin, who was just about to open his first kung-fu school in the area.

Brown began to devote more and more time to kung-fu training and a year later gave up a five-figure salary as a computer specialist to teach at Lin's for less than $100 a week.

Today he's the senior disciple at Lin's - the equivalent of "Number One Son" in the martial arts hierarchy. And at 5-foot-7 and 135 pounds, he has absolute confidence in his ability to handle any encounter.

"I had a slight run-in with a fellow a while back that could have easily turned into a street fight," the 29-year-old remembered. "But I ran through the fight mentally and I had the cat beaten in 10 seconds. I knew I could beat him, so what was the use fighting?"

It was the mental aspect of kung-fu that attracted Brown.

"Karate is based on straight-ahead motion," he explained, "while kung-fu is a system based on out-thinking and out-maneuvering the opponent." (The term kung-fu means simple "skill" or "work" in chinese. Lin's teaches wushu kung-fu which means "combat skill.")

"Karate teaches you to keep coming, absorbing rather than blocking or dodging your opponent's blows. It places a premium on power," Brown said." That style makes it harder to defeat a bigger opponent.

"In kung-fu you spar in a circular, sweeping motion, yielding away from the main force of the attack until you find an opening. Since I don't like to get hit, I went with kung-fu."

When he began competing in martial arts tournaments, Brown found that judges accorded kung-fu second-class status.

"The referees would often stop matches involving karate and kung-fu styles and go over to the kung-fu man to show him the right way to fight. There were complaints that the kung-fu student was not fighting, that he was just doing this funny little dance. But to me, punching and kicking wildly is street fighting, not a martial art."

So Brown competed in tournaments as a lobbyist for his art, testing his style against others. He has won over 100 trophies in weapons, sparring (kata) and forms.

Full-contact karate is a recent invention of promoters hoping to cash in on the burgeoning popularity of martial arts; kung-fu matches have always been full contact, but unlike full-contact karate there are no weight classes in kung-fu.

Brown won the East Coast kung-fu championship in 1974. He had to bear four oppponents in matches ended either by time limit or, more often, by one man being unable to continue.

He has not fought competitively since, prefering to concentrate on forms and weapons. He is currently ranked No. 1 on the East Coast in both categories by one magazine. His favorite weapon is the "white eyebrow" or long staff, which he chose to master because not many martial artists are proficient at it. Single and double broadswords, spears and the steel whip are also in his arsenal.

It is a rare weekend that Brown has not been invited to compete in, referee or judge some tournament.

He spends 10 hours a day at one of Lin's two locations (Georgia Avenue NW and Eastover Shopping Center). As head instructor he teaches advanced students, trains and reviews instructors, talks with new students.

Lin's is one of the few kung-fu schools that doesn't offer belts or sashes to indicate a student's prowess.

"We're all still students at the school," Brown said. "Granting a belt might give someone a false sense of security. We don't ever want anyone to feel he's learned all there is to know."

But Brown is trying to learn all of it.

"I guessed you could say that martial arts is my mistress - it keeps me away from my wife and home." He has a 380-book collection of "every martial arts book that's ever been written" and an extensive film library, including films he has taken at tournaments.

A Chinese studies major at Federal City College, Brown also devours books on ancient Chinese life and would like someday to make a trip to China. "I'm even into Chinese cooking," he said.

"I think that if you really want to be good at something you must not only perfect the techniques, but also know the culture and philosophy behind it."