The authors examine the implications of health and personality characteristics for late-life marital conflict using data from the 2010–2011 wave of the National Social Life Health and Aging Project, a nationally representative study with data on both partners in 955 marital and cohabitational dyads. Using these data, they relate characteristics of husbands to characteristics of their wives and vice versa. Wives with husbands in fair or poor physical health were more likely to report high levels of marital conflict, but the reverse was not true. Similarly, wives reported more conflict when their husbands were high on Neuroticism, high on Extraversion, and low on a new measure the authors call Positivity. The findings suggest noteworthy gender differences between men and women in the associations between individual characteristics and levels of marital conflict. The authors point to differences between husbands' and wives' marital roles as a contributor to these differences.