The family structure of older Japanese is projected to change dramatically as a result of very low fertility, increasing levels of non-marriage, childlessness, and divorce, and declining intergenerational coresidence. To provide an empirical basis for speculation about the implications of projected increases in single-person and couple-only households, we use two sources of data to describe relationships between family structure and the physical and emotional well-being of Japanese men and women age 60 and above. We find that marriage is positively associated with self-rated health and emotional well-being among older men but not women. In contrast to expectations, however, we find only limited evidence that the presence of children contributes to well-being. Taken as a whole, our results suggest that declines in marriage may have negative implications for the well-being of older Japanese men while the implications of declines in fertility and intergenerational coresidence may be less than popularly believed.