Although research has documented associations between grandparenthood and grandparents' mental health, the basis of these associations has not been extensively explored. This study asked grandparents to describe their relationship with one grandchild and that grandchild's parents; the selected grandchild was the oldest grandchild in the two-parent household geographically closest to the grandparent. Demographic variables, measures of closeness to the grandchild and the grandchild's parents, and perceptions of the grandparent-grandchild relationship were evaluated as predictors of grandparents' mental health. Participants were 301 grandparents between the ages of 43 and 86. The results revealed two significant predictors of morale: grandparents reporting good health and frequent intergenerational contact expressed highest morale. There were three significant predictors of scores on the Life Satisfaction Index A: grandparents reporting good health, married grandparents, and those reporting greatest attitudinal similarity expressed greatest life satisfaction. Finally, there were three significant predictors of self-esteem: grandparents reporting good health, married grandparents, and those expressing low levels of the symbolic importance factor expressed highest self-esteem. Demographic background and selected aspects of family solidarity were more strongly associated with mental health than were reactions to grandparenthood. (NB)