The purpose of this study was to investigate the factors associated with instrumental support (i.e., economic and practical support) from parents to their adult children. We examined both parents’ attitudes toward instrumental support for adult children and parents’ actual provision of instrumental support. From the data of the 2010 second National Survey of Korean Families, we selected 532 mothers and 524 fathers who were married and had at least one adult child aged over 25. Multiple regression analyses by the parents’ gender showed that fathers were more likely to agree with instrumental support for adult children in general when they had unmarried children, had a lower household income level, had a lower evaluation of their socio-economic class, were satisfied with their own household economic situation, had positive attitudes toward caregiving for elderly parents, and were satisfied with their couple relationships. For mothers, they were more likely to agree with instrumental support for adult children in general when they had positive attitudes toward caregiving for elderly parents, were satisfied with their couple relationships, and perceived their child as someone to rely on in times of difficulties. Our analyses of the actual provision of support indicated that fathers tended to provide more support when they perceived that they were healthy, had unmarried children, were less satisfied with their household economic situation, had negative attitudes toward child-rearing, and reported a higher quality of parent-child relationship. For mothers, they were more likely to provide actual support when they were healthy, had unmarried children, had a higher level of household income, were financially preparing for later life, and less satisfied with their couple relationships. The findings of this study imply that it is imperative to distinguish the attitudes toward support from the actual provision of support and to also consider parents’ gender in the literature on instrumental support for adult children.