Even though more than half of couples now do it, compared with only 10% 30 years ago, living together before marriage still is linked to higher rates of troubled unions, divorce, and separation, Pennsylvania State University, University Park, researchers have found.

Comparing data on 1,425 people married between 1964-80 when cohabitation was less common and between 1981-97 when it was more customary, they observed that, in both groups, cohabiters reported less happiness and more marital conflict than noncohabiters. Also, couples who lived together before marriage were more likely to divorce.

"It had been consistently shown in the past that, contrary to the popular belief that living together will improve a person's ability to choose a marriage partner and stay married, the opposite is actually the case," states Claire M. Kamp Dush, doctoral candidate in human development and family studies.

Although all the reasons why cohabitation and troubled unions are related remain unknown, the researchers report that their data and a review of the literature suggest that both personal characteristics and the experience of cohabitation play important roles. People choose riskier partners since they think co-habitation will be easier to break up than marriage. However, once a couple sets up house, the fact that they share possessions, pets, and children and have invested time in their relationship may propel them to marry.

Moreover, the researchers contend that living together in an unconventional relationship can make people less religious and may encourage them to develop problematic interpersonal skills and to spend less time resolving problems or providing support to their partners.