In the days before his death, Douglas Ealey Jr. planned his costume for a homecoming celebration at Suitland High School, took college entrance examinations and tackled student council business.

"He didn't sound any different," said Trey Lanier, a senior at Eleanor Roosevelt High School who worked with Ealey on the Prince George's County Regional Association of Student Governments and talked to him the night before he died.

"He was Doug," said Hope Butler, another friend.

But on the morning of Nov. 5, Ealey -- the student member of the Prince George's County Board of Education -- took his life with a handgun, stunning friends and school officials who saw him as optimistic and well-adjusted.

Ealey was one of thousands of teen-agers in this country who commit suicide each year. Experts debate why the number of teen-agers who take their lives has tripled since 1950, pointing to social changes, such as the breakup of the traditional family. Others say the increase in families with two working parents has caused more isolation among young people than in previous generations.

Many of Ealey's adolescent friends conceded in interviews following his death that they are frightened about his mysterious decision to end his life. Although they said they are happy and do not contemplate such a decision, they have their theories about why teen-age suicides have climbed.

"A lot of pressures are being put on us, from our parents, from the school system," said Lanier, 16, who is vice president of the county's student government organization. "My parents are always on my back about grades, girlfriends. I can't get any break from them."

Those who were close to Ealey said he showed no signs of stress despite his long list of student government responsibilities, accelerated courses and the ordinary, busy social life of a popular teen-ager.

But while they dismissed the pressures of leadership as a factor in Ealey's death, several of his student government colleagues complained about their responsibilities.

"Last night I was in total depression," said 15-year-old regional student government treasurer Stuart Rosenberg last week. "Sometimes with a job, plus school . . . I figure all these things I have to do and there's no time to do it. Why is there all this pressure on me? Something's got to go."

He added, quickly: "I'm not suicidal or anything."

Hope Butler, president of the county student government organization and a close friend of Ealey's, does not see a common denominator among teen-age suicides, which some experts say may be three times the government estimate of 5,200 for last year because of suicides reported as accidents.

The reasons for suicide "apply differently to different people," Butler said. "Different rules may apply to student leaders."

Another high school student said he thinks all teen-agers are facing higher expectations. "Stress is a big factor. There are more things . . . SATs, that sounds sort of crazy, but things are so competitive now, like you play the game or you get lost in the crowd," said Daryl Fitzgerald, a 16-year-old senior at Eleanor Roosevelt and county student government executive board member.

Ealey's friends, many of whom had not been touched by death before, said they were frightened, as well as saddened, by his suicide.

"I think of myself as being a secure person, but I doubt if Doug ever thought about it suicide ," said Troy Bell, 17, a senior at Oxon Hill Science and Technology Center. "If I'm secure now, is there something to push me to that point that I would consider it?"

Lanier said the attention on the national problem has unintentionally transformed the issue of teen-age suicide into a subject of sick humor. "We have this joke at school. 'How's a girl's name ? Has she killed herself yet?' We joke about it, but we all feel bad and wonder how it could get that bad," he said.