Karen Klaber Oppenheim Mason died peacefully at home on April 11, 2024. Her son, David, and her husband of 30 years, John Sibert, were with her. She was 81 years old. 

Karen became a member of IUSSP in 1976. She was the founding co-chair of the IUSSP Committee on Gender and Population,1990-1994. The Committee (Brigida Garcia, Shireen Jejeebhoy, An-Magritt Jensen, Paulina Makinwa) organized several seminars over its tenure: Gender and Family Change in Industrialised Countries (Rome, 1992); Women, Poverty and Demographic Change (Oaxaca, Mexico, 1994) and Women and Demographic Change in sub-Saharan Africa (Dakar, Senegal, 1993). The Committee also published several volumes authored or co-edited by Karen or other committee members. For example, Karen and An-Magritt Jensen integrate debates about how improvements in women’s economic opportunities affected marriage and union stability in the post-World War II era. They make a compelling case for collecting data on stability and change in individuals’ – both women’s and men’s – attitudes about the value of marriage to understand temporal change in the timing of marriage and cross-sectional variation. These issues are also central in The Changing Family in Comparative Perspective: Asia and the United States (ed. with Noriko O. Tsuya and Minja Kim Choe, 1998), which broadened the field of inquiry to comparative research on several East Asian countries.


Karen was PAA president in 1997. She received PAA’s Harriet Presser award in 2011 honoring her career-long contributions to the study of gender and demography. This professional recognition is matched by Karen’s leadership in breaking down institutional and informal barriers to women’s opportunities in academia and in “real” life.  

Karen drifted (her word) into demography. She attended Reed College on a scholarship. There she took classes in sociology from John Pock, who taught several cohorts of undergraduates who became quantitative sociologists and demographers. Karen went to graduate school at the University of Chicago, where she worked with Robert (Bill) Hodge, another “Reedie” who taught empirical approaches to sociology, and James (Jim) Davis, who trained her in survey methods. Her dissertation was on Voting in Recent American Presidential Elections (1970). It posed the problem of temporal change in social indicators in a way that initiated the search in sociology and demography for additive representations of change attributable to aging, to birth cohort, and to historical change (period). 

Karen’s first job was in the Sociology Department at the University of Wisconsin-Madison. It was there that she felt that she became a demographer. She also began to focus her teaching and research on gender and gender inequality. She soon moved with her then-husband William (Bill) Mason to North Carolina where she conducted research on women’s labor force participation and fertility at the Research Triangle Institute.   

The connections among fertility, women’s paid and unpaid work, and childcare became a driving theme in Karen’s research. While her earlier publications examined these issues within the United States, she soon expanded her attention to women’s experiences in low-income settings. She took seriously the idea that both institutional and individual factors affect women’s opportunities and reproductive health. Her analytic approach pushed back on sometimes fuzzy concepts, such as norms and family-size ideals, to produce theoretically informed research designs. 
In 1973, Karen joined the University of Michigan’s Sociology Department and Population Studies Center, where she moved through the academic ranks to Professor. She was a role model for the growing number of female graduate students in demography.  While at Michigan, Karen became involved, first as a reviewer in a program directed by her former student, Mary Kritz, and then as a recipient of research support from The Rockefeller Foundation’s program in women’s status and fertility. Karen’s The Status of Women: A Review of Its Relationships to Fertility and Mortality (Rockefeller, 1985) shows the hallmarks of Karen’s insightful attention to the meaning of concepts and the empirical implications of theoretical debates. Sociological Forum published a more concise version in 1986, but the Rockefeller report remains a classic among those working at the intersection of gender and demography. 

In 1991, Karen became the Director of the Population Studies Program at the University of Hawaii, later becoming Director of the Program on Population at the East-West Center, in Honolulu. There Karen continued her leadership of the innovative Status of Women and Fertility (SWAF) study, originally begun while she was at the University of Michigan. The 5-country study included India, Malaysia, Pakistan, the Philippines, and Thailand, and involved collaborators Napaporn Chayovan, Shireen Jejeebhoy, Lin Lean Lim, Corazon Raymundo, Zeba Sathar, and Herbert Smith. The design was an ambitious cross-country study in which communities and individuals were units of observation to support studies of the contexts and individual circumstances governing the effects of women’s power and autonomy on fertility. It pioneered the use of multiple indicators of women’s agency in ways that are relevant cross culturally and across countries. 

Karen’s PAA presidential address, “Explaining Fertility Transitions” (1997), outlines an approach to understanding transitions from high to low fertility that takes into account the importance of individuals’ perceptions of such phenomena as child survival. It offers strategies to improve knowledge of why fertility declined in some places more quickly and for different reasons than in others. It also undertook a nuanced description of limitations in extant theories of fertility transition at the same time. Among the fertility theories Karen criticized was the microeconomics approach developed by economist Gary Becker, who received a PAA award a few minutes before Karen began her presidential address. It was a memorable moment of live theater, which Karen handled with her usual poise and aplomb.


Karen’s career took a conscious turn, not a drift, in 1999 when she moved to the World Bank as Director of the Gender and Development Program. There she put into practice many of the principles that animated her research career. Her leadership and organizational skills enabled her to foster programs at the intersection of academic and program knowledge to enhance women’s reproductive autonomy. Karen served as program director until 2004 when she returned to the East-West Center as Adjunct Senior Fellow, a position she held until she retired in 2012.


Karen made field-changing contributions to demography and population studies by transplanting to them the strongest elements of sociology. She was known in her professional life for her clear thinking, persuasive writing, and ability to get things done. She was an effective leader who excelled in collaborative settings.


In her personal life, Karen had many joys, especially her family. She took great pleasure in her wide network of friends, including her students and colleagues. She loved to cook and enjoyed traveling all over the world as well as local excursions. Karen also loved to make pottery and to view others’ creations. She is survived by her husband John, son David, stepdaughter Annika, brother David, and three granddaughters who lit up her life. We share their loss.


Modified version of a PAA memorial statement, contributed by: Judith A. Seltzer, UCLA; Shireen Jejeebhoy, Aksha Centre for Equity and Wellbeing and International Institute for Population Sciences, Mumbai; Andrew Mason, University of Hawaii; Herbert L. Smith, University of Pennsylvania; and Noriko O. Tsuya, Keio University.