["Japanese Psychological Research, EarlyView. ", "\nAbstract\nFit‐focused secondary control (FFSC)—the process of adjusting some aspect of the self and accepting circumstances as they are—is an important coping strategy for older adults' well‐being. However, for older married couples, it is unclear whether one partner's FFSC is related to both their own and their partner's psychological well‐being and whether cultural differences exist in this relationship. An online survey was administered to 199 Japanese and 208 American older married couples to assess their positive affect, negative affect, marital satisfaction, and their adjustment and acceptance strategies to marital disagreements and pleasurable shared activities. The actor–partner interdependence model showed that husband and wife FFSC was positively associated with individual and partner positive affect and marital satisfaction but negatively associated with individual negative affect. Cultural differences were observed: the association between husband and wife FFSC and partner marital satisfaction was stronger for Japanese couples than for American couples. These findings suggest that FFSC predicts the psychological well‐being not only of individuals but also of those around them.\n"]