In this study, we explored the nature of the relationship between custodial grandparents' perception of control over caregiving outcomes and their discipline behavior with grandchildren. Perceived control moderated the relationship between frequency of difficult child behaviors and grandparents' use of strict disciplinary practices. However, unexpectedly, a high frequency of difficult grandchild behavior was associated with greater use of strict, even harsh, discipline among grandparents with high rather than low perceived control. This pattern was evidenced across the total sample; however, it was especially pronounced in African-American grandparent families. Among custodial grandparents, especially among African-American grandparents, it is possible that both nurturing and aggravation are intensified by the re-parenting experience. Between-group differences may reflect the fact