In this study, we examined within-person variability in maternal sensitivity among a culturally diverse sample of high-risk mother-infant dyads (N = 25). We also examined incremental increases in effect sizes between maternal sensitivity and two related variables, attachment state of mind and child removal from the home, as a function of increasing observations of maternal sensitivity. The dyads were videotaped during 10 1-hour-long home visits and maternal sensitivity was coded using the abbreviated (25-item) version of the Maternal Behavior Q-Sort (MBQS). Attachment state of mind was assessed using the Adult Attachment Interview (AAI). Within-person variability in maternal sensitivity was greater for nonautonomous mothers compared to autonomous mothers. Mothers who were relatively low in maternal sensitivity were more likely to be nonautonomous and also more likely to have their child removed from their home by child protective services. Results from data sampling trials showed incremental increases in these effect sizes as the number of observations of maternal sensitivity increased. Fewer observations of maternal sensitivity resulted in systematic underestimates of effect sizes between maternal sensitivity and related variables. We discuss the implications for maltreatment researchers and interventionists.