Having an unhappy youth or a bleak middle age has little effect on whether a man will be happy during retirement, according to a new study. And a prosperous adulthood is no assurance of contentment after one's working years have ended.

Even a large pension, the study found, is less important in assuring contentment than generally believed. In other words, being retired, for many people, may be the start of something entirely new. 

The report is in the April issue of the American Journal of Psychiatry.

Researchers followed 280 socially disadvantaged men from adolescence until an average age of 75, interviewing them with questionnaires every other year and administering physical examinations every five years to determine their biological and social risk variables, their age at retirement and their satisfaction with being retired.

Only 34 percent of the men retired before age 62, but the lower the skill level of the job, the earlier the men quit working. Early retirement was also associated with poor physical or mental health. Those with the lowest incomes and the lowest pensions retired earliest. 

The researchers found that, in addition to a happy marriage and a sense of purpose, the most important factor in a happy retirement was learning how to "play" again. The scientists define play as engaging in activities that are highly gratifying, lack any economic significance, cause no social harm and do not necessarily lead to praise or recognition from others. 

In other words, many of the factors that allow happiness in retirement appear to be quite different from those that assure a contented and economically secure middle age.

The researchers were most surprised by the finding that happiness in retirement depended neither on being free from physical disability nor on having a large income. Instead, the answers to two questions were most important: "What are your most enjoyable activities?" and "What gives your life a sense of purpose?" 

Men who found retirement satisfying were more than twice as likely to report enjoying relationships, volunteering, and having hobbies among their favorite activities as were those who found retirement unrewarding. The happiest men were more likely to answer by giving specific examples of rewarding or creative activities: "watching my grandchildren," "writing my memoirs" and "playing the piano" were typical responses. 

Men who were unhappily retired tended to respond with what the researchers call "autistic activities" like "watching television" or "gambling" or "caring for myself." For example, 43 percent of the happiest retirees said they found purpose in community service, while only 7 percent of those who found retirement unsatisfying did.

"Maybe it's surprising, and maybe it isn't," said Dr. Kenneth J. Mukamal, a co-author of the study, "but a lot of what one can do to assure a happy retirement involves becoming emotionally mature, taking the time to find activities that stimulate us, make us broader and deeper and more complex, and activities that involve others, and which in many cases the only obvious benefit is to others. It has a lot less to do with income." 

Dr. Mukamal, an assistant professor of medicine at Harvard, cautioned that the study has weaknesses. The sample included no women, and all the men were selected as teenagers when they lived in Boston. All were Caucasian, and their parents were educationally disadvantaged. 

Moreover, the sample excluded a disproportionate number of depressed, alcoholic and physically disabled men who dropped out of the study or who were otherwise unable to respond adequately. The authors also acknowledge that their measures of retirement satisfaction — questionnaires and interviews — were relatively crude.

Still, they believe the study shows that certain attitudes and practices in retirement can provide a new start for some men whose middle years were less than successful. The researchers' initial hypothesis — that retirement satisfaction would depend on the same factors that led to a happy and prosperous midlife — remained unproven.