Women who have cohabited more than once -- so-called "serial cohabitors" -- are less likely to marry than women who cohabit once. And if they do marry, they are twice as likely to divorce than women who lived only with their eventual husbands, according to a new Cornell study.

"Even when conventional social, economic and demographic variables are controlled for in the analyses, serial cohabitation placed women at much greater risk of remaining single," said Daniel T. Lichter, director of the Bronfenbrenner Life Course Center and the Ferris Family Professor in the Department of Policy Analysis and Management in Cornell's College of Human Ecology.

The study, an analysis of 4,832 women -- of which 1,795 had cohabited -- from the 1979-2000 National Longitudinal Survey of Youth, conducted with Zhenchao Qian, professor of sociology at Ohio State University, is published in the November issue of the Journal of Marriage and the Family.

The study also found that about 15 to 20 percent of cohabiting women had lived with more than one man, and that a disproportionate share of serial cohabitors were from economically disadvantaged groups, especially those with low education. Furthermore, the more men that the women lived with, the less likely they were to get married or stay married.

"From a policy standpoint, our results suggest that the government's effort to promote marriage among serial cohabitors -- especially disadvantaged cohabiting women -- may be much more difficult than previously thought," Lichter said.

Although many cohabiting women marry, serial cohabitors tend to "face serious economic and family constraints to marriage that simply do not exist among childless women who cohabit only with men they marry. For example, serial cohabitation may reflect demographic shortages of men who are good providers or companions (e.g., men with good jobs, who are faithful or who are drug free). Women may cycle between relationships because their partners are not good 'marriage material.' If so, serial cohabitation may be less responsive to specific policy initiatives."

He added: "The results suggest the need to balance the government's current preoccupation with marriage promotion with greater support of 'at risk' unions that marriage promotion initiatives have helped create."

Other studies have shown that about 54 percent of first unions begin with cohabitation and that 56 percent of women age 19-44 who married had previously cohabited.

The study was funded, in part, by the National Institute of Child Health and Human Development.