Perceptions of mothers’ favoritism and disfavoritism in adulthood are strong predictors of psychological well-being; however, it is not known whether perceptions that are sustained across time increase the risk for depressive symptoms beyond those found at a single point in time. In the present paper, we use data collected from 479 adult children nested within 219 later-life families as part of the first and second waves of the Within-Family Differences Study to explore the relative risk of single-time versus sustained perceptions of mothers’ differentiation. Preliminary findings reveal that adult children’s perceptions of both favoritism and disfavoritism are relatively stable, consistent with findings based on mothers’ own reports. Consistent with theories of cumulative stress, perceptions of sustained favoritism and disfavoritism were found to be stronger predictors of depressive symptoms than were perceptions at any single point. The effects are particularly strong for Black offspring who perceive sustained disfavoritism.